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<SEC-DOCUMENT>0000950103-05-001247.txt : 20050418
<SEC-HEADER>0000950103-05-001247.hdr.sgml : 20050418
<ACCEPTANCE-DATETIME>20050418172124
ACCESSION NUMBER:		0000950103-05-001247
CONFORMED SUBMISSION TYPE:	SC 13D
PUBLIC DOCUMENT COUNT:		2
FILED AS OF DATE:		20050418
DATE AS OF CHANGE:		20050418

SUBJECT COMPANY:	

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIOSOURCE INTERNATIONAL INC
		CENTRAL INDEX KEY:			0000860451
		STANDARD INDUSTRIAL CLASSIFICATION:	IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES [2835]
		IRS NUMBER:				770340829
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	005-52879
		FILM NUMBER:		05757522

	BUSINESS ADDRESS:	
		STREET 1:		542 FLYNN ROAD
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012
		BUSINESS PHONE:		8059870086

	MAIL ADDRESS:	
		STREET 1:		542 FLYNN ROAD
		CITY:			CAMARILLO
		STATE:			CA
		ZIP:			93012

FILED BY:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			BIO RAD LABORATORIES INC
		CENTRAL INDEX KEY:			0000012208
		STANDARD INDUSTRIAL CLASSIFICATION:	LABORATORY ANALYTICAL INSTRUMENTS [3826]
		IRS NUMBER:				941381833
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	FILING VALUES:
		FORM TYPE:		SC 13D

	BUSINESS ADDRESS:	
		STREET 1:		1000 ALFRED NOBEL DR
		CITY:			HERCULES
		STATE:			CA
		ZIP:			94547
		BUSINESS PHONE:		5107247000
</SEC-HEADER>
<DOCUMENT>
<TYPE>SC 13D
<SEQUENCE>1
<FILENAME>apr0805_13d.htm
<TEXT>



<HTML>
<HEAD>
   <TITLE>13D</TITLE>
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<B><FONT size=4 face="serif">SECURITIES AND EXCHANGE COMMISSION</FONT></B><br>

<B><FONT size=2 face="serif">Washington, D.C. 20549 </FONT></B></P><HR NOSHADE SIZE=1 width=15%>
<P align="center">
<B><FONT size=4 face="serif">SCHEDULE 13D</FONT></B><br>

<B><FONT size=2 face="serif">(Rule 13d-101) </FONT></B></P>
<P align="center">
<B><FONT face="serif">INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT TO RULE <br>
13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO RULE 13d-2(a) </FONT></B></P>


<table width="100%"  border="0" cellspacing="0" cellpadding="0">
     <tr>
          <td align="center"><b><font size=4 face="serif">B</font></b><b><font size=3 face="serif">IO</font></b><b><font size=4 face="serif">S</font></b><b><font size=3 face="serif">OURCE </font></b><b><font size=4 face="serif">I</font></b><b><font size=3
face="serif">NTERNATIONAL</font></b><b><font size=4 face="serif">,</font></b><b><font size=3 face="serif"> </font></b><b><font size=4 face="serif">I</font></b><b><font size=3 face="serif">NC</font></b><b><font size=5 face="serif">. </font></b></td>
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          <td align="center"><hr noshade size=1>               </td>
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          <td align="center"><font size=1 face="serif">(Name of Issuer) </font></td>
     </tr>
     <tr>
          <td align="center">&nbsp;</td>
     </tr>
     <tr>
          <td align="center"><b><font face="serif">Common Stock, par value $.001</font></b></td>
     </tr>
     <tr>
          <td align="center"><hr noshade size=1>               </td>
     </tr>
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          <td align="center"><font size=1 face="serif">(Title of Class of Securities) </font></td>
     </tr>
     <tr>
          <td align="center">&nbsp;</td>
     </tr>
     <tr>
          <td align="center"><b><font size=2 face="serif">09066H104</font></b></td>
     </tr>
     <tr>
          <td align="center"><hr noshade size=1>               </td>
     </tr>
     <tr>
          <td align="center"><b><font size=1 face="serif">(CUSIP Number)</font></b></td>
     </tr>
     <tr>
          <td align="center">&nbsp;</td>
     </tr>
     <tr>
          <td align="center"><p><b><font size=2 face="serif">Sanford S. Wadler,
                              Esq. </font></b><br>
                              <b><font size=2 face="serif">Bio-Rad Laboratories, Inc.</font></b><br>
                              <b><font size=2 face="serif">1000 Alfred Nobel Drive </font></b><br>
                              <b><font size=2 face="serif">Hercules, California 94547</font></b><br>
                              <b><font size=2 face="serif">(510) 724-7000 </font></b></p>
               <p><b><font size=2 face="serif">Copy
                    to: </font></b></p>

                         <b><font size=2 face="serif">William M. Kelly </font></b><br>
                         <b><font size=2 face="serif">Davis Polk &amp; Wardwell </font></b><br>
                         <b><font size=2 face="serif">1600 El Camino Real </font></b><br>
                         <b><font size=2 face="serif">Menlo Park, California 94025</font></b><br>
                         <b><font size=2 face="serif">(650) 752-2000</font></b></p></td>
     </tr>
     <tr>
          <td align="center"><hr noshade size=1>               </td>
     </tr>
     <tr>
          <td align="center"><font size=1 face="serif">(Name, Address and Telephone
                    Number of<br>
               Person Authorized to Receive Notices<br>
              and Communications)</font></td>
     </tr>
     <tr>
          <td align="center">&nbsp;</td>
     </tr>
     <tr>
          <td align="center"><b><font size=2 face="serif">April 8, 2005 </font></b></td>
     </tr>
     <tr>
          <td align="center"><hr noshade size=1>               </td>
     </tr>
     <tr>
          <td align="center"><font size=1 face="serif">(Date of Event which Requires
               Filing of this Statement)</font><font size=2 face="serif">&nbsp; </font></td>
     </tr>
     <tr>
          <td align="center">
  <tr>
                    <td align="center">&nbsp;</td>
  </tr>
               <tr>
                    <td align="center"><hr noshade size=1 width=15% align=center></td>
               </tr>
</table>               </td>
     </tr>



<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of Rule 13d-1(e),
13d-1(f) or 13d-1(g), check the following box </FONT><font size=2 face="wingdings">o</font><FONT size=2 face="serif">. </FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<I><FONT size=2 face="serif">Note</FONT></I><FONT size=2 face="serif">. Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. </FONT><I><FONT size=2
face="serif">See</FONT></I><FONT size=2 face="serif"> Rule 13d-7 for other parties to whom copies are to be sent. </FONT></P>
<div align="center"><FONT size=2 face="serif">Page 1 of 5 </FONT>
     <br>
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     <table width="90%" border="0" cellspacing="0" cellpadding="10">
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               <td width="25%" align="left" valign="middle" STYLE="border-color: #000000; border-top-style: solid; Border-top-Width: 1.0pt;
border-bottom-style: solid; Border-bottom-Width: 1.0pt; Border-left-Width: 1.0pt; border-left-style: solid; Border-right-Width: 1.0pt; border-right-style: solid"><strong><font size="2" face="Times New Roman, Times, serif">CUSIP
                              No.


                              <strong>09066H104 </strong> </font></strong></td>
               <td align="center" valign="middle"><font size="3" face="Times New Roman, Times, serif"><strong>13D</strong></font></td>
               <td STYLE="border-color: #000000; border-top-style: solid; Border-top-Width: 1.0pt;
border-bottom-style: solid; Border-bottom-Width: 1.0pt; Border-left-Width: 1.0pt; border-left-style: solid; Border-right-Width: 1.0pt; border-right-style: solid"width="25%" align="left" valign="middle"><B><FONT SIZE="2">Page
                              2 of 5 Pages </FONT></B></td>
          </tr>
     </table>
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<br>
<div align=center>
     <table width="90%" border="1" cellpadding="5" cellspacing="0" bordercolor="#000000">
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">1</font></td>
               <td colspan="3" align="left" valign="top"><p><font size="2" face="Times New Roman, Times, serif">NAME
                              OF REPORTING PERSONS</font><br>
                              <font size="2" face="Times New Roman, Times, serif">Bio-Rad
                              Laboratories, Inc. <br>
                              I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS
                                   (ENTITIES ONLY)<br>
                                   94-1381833 </font></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">2</font></td>
               <td colspan="3" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">CHECK
                         THE APPROPRIATE BOX IF A MEMBER OF A GROUP*</font>
                    <div align=right><font size="2" face="Times New Roman, Times, serif">(a)</font>&nbsp;<font size=2 face=wingdings>o&nbsp;</font><br>
                         <font size="2" face="Times New Roman, Times, serif">(b)</font>&nbsp;<font size=2 face=wingdings>o&nbsp;</font></div></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">3</font></td>
               <td colspan="3"><font size="2" face="Times New Roman, Times, serif">SEC
                         USE ONLY</font><br>
                    <br> </td>
          </tr>
          <tr>
               <td align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">4</font></td>
               <td colspan="3"><font size="2" face="Times New Roman, Times, serif">SOURCE
                         OF FUNDS* <br>
                    <br>
                    </font><FONT size=2 face="serif">WC</FONT></td>
          </tr>
          <tr>
               <td align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">5</font></td>
               <td colspan="3" VALIGN="TOP"><FONT SIZE="2" FACE="Times New Roman, Times, serif">CHECK
                         BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT
                         TO ITEM 2(d) or 2(e)<BR>
                    <br>
                    </FONT>
                    <div align=right><FONT SIZE="2" FACE="Wingdings">o&nbsp;</FONT> </div></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">6</font></td>
               <td colspan="3"><font size="2" face="Times New Roman, Times, serif">CITIZENSHIP
                         OR PLACE OF ORGANIZATION<br>
                    <br>
                    </font><FONT size=2 face="serif">Delaware</FONT></td>
          </tr>
          <tr>
               <td colspan="2" rowspan="4" align="center" valign="middle"><font size="2" face="Times New Roman, Times, serif">NUMBER
                         OF SHARES<br>
                    BENEFICIALLY OWNED BY<br>
                    EACH REPORTING PERSON<br>
                    WITH </font></td>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">7</font></td>
            <td width="57%" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">SOLE
                         VOTING POWER<br>
<br>
                    </font><FONT size=2 face="serif">665,639</FONT></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">8</font></td>
               <td width="57%" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">SHARED
                         VOTING POWER<br>
                    <br>
                    </font><FONT size=2 face="serif"> 0 </FONT></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">9</font></td>
            <td width="57%" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">SOLE
                         DISPOSITIVE POWER<br>
<br>
                    </font><FONT size=2 face="serif">665,639</FONT></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">10</font></td>
               <td width="57%" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">SHARED
                         DISPOSITIVE POWER<br>
                    <br>
                    </font><FONT size=2 face="serif">0</FONT></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">11</font></td>
            <td colspan="3" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">AGGREGATE
                         AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON<br>
<br>
                    </font><FONT size=2 face="serif">665,639</FONT></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">12</font></td>
               <td colspan="3" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">CHECK
                         BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                         SHARES*</font>
                    <div align=right><font size=2 face=wingdings>o&nbsp;</font></div>
               <font size="2" face="Times New Roman, Times, serif">&nbsp;</font><br></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">13</font></td>
            <td colspan="3"><font size="2" face="Times New Roman, Times, serif">PERCENT
                         OF CLASS REPRESENTED BY AMOUNT IN ROW (11) <br>
<br>
               </font><font size="2" face="serif">6.8</font></td>
          </tr>
          <tr>
               <td width="5%" align="center" valign="top"><font size="2" face="Times New Roman, Times, serif">14</font></td>
               <td colspan="3" align="left" valign="top"><font size="2" face="Times New Roman, Times, serif">TYPE
                         OF REPORTING PERSON*<br>
                    <br>
                    </font><FONT size=2 face="serif">CO</FONT></td>
          </tr>
     </table>
</div>
<br>
<br>

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<P>
  <B><I><FONT size=2 face="serif">Item 1. Security and Issuer. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">The class of equity securities to which this statement relates is the common stock, $ .001 par value per share (the &#147;Common Stock&#148;), of BioSource International, Inc., a Delaware corporation (the &#147;Issuer&#148;). The principal executive offices of the Issuer are located at 542 Flynn Road, Camarillo, California 93012. </FONT></P>
<P> <B><I><FONT size=2 face="serif">Item 2. Identity and Background. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">This statement on Schedule 13D is being filed by Bio-Rad Laboratories, Inc., a Delaware corporation (&#147;Bio-Rad&#148;). </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Bio-Rad manufactures and supplies the life science research, healthcare, analytical chemistry and other markets with a broad range of products and systems used to separate complex chemical and biological materials and to identify, analyze and purify their components. The address of the principal business and the principal office of Bio-Rad is 1000 Alfred Nobel Drive, Hercules, California 94547. The name, business address, present principal occupation or employment and citizenship of each director and executive officer of Bio-Rad is set forth on Schedule A. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">During the last five years, none of Bio-Rad, and to the best of Bio-Rad&#146;s knowledge, any of the persons listed on Schedule A attached hereto, has been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or has been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject, to federal or state securities laws or finding any violation with respect to such laws. </FONT></P>
<P> <B><I><FONT size=2 face="serif">Item 3. Source and Amount of Funds or Other Consideration. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Bio-Rad has purchased the shares of Common Stock it beneficially owns in open market transactions at an aggregate purchase price of approximately $4,971,266. These purchases were funded through internally generated funds. </FONT></P>
<P> <B><I><FONT size=2 face="serif">Item 4. Purpose of Transaction. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Bio-Rad acquired the shares of Common Stock to which this statement on Schedule 13D relates for the purpose of acquiring a significant equity position in the Issuer. In addition, Bio-Rad believed that ownership of the shares could facilitate a business combination between the Issuer and Bio-Rad. Bio-Rad has had discussions with the Issuer and other investors in the Issuer concerning further acquisitions of the Common Stock and a merger of the Issuer with Bio-Rad, and on April 6, 2005, Bio-Rad sent a letter (the &#147;Letter&#148;) to the Issuer proposing that Bio-Rad acquire all of the Issuer&#146;s outstanding shares for $8.50 per share in cash. The Letter is attached hereto as Exhibit 1. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Bio-Rad intends to review its holdings in the Issuer on a continuing basis and, depending upon the price and availability of the Common Stock, subsequent developments affecting the Issuer, the business prospects of the Company, general stock market and economic conditions, tax considerations and other factors deemed relevant, may at any time (as permitted by applicable law) determine to acquire through open market purchases or otherwise additional shares of Common Stock; sell shares of Common Stock through the open market or otherwise; or engage or participate in a transaction or series of transactions with the purpose or effect of influencing control of the Issuer. Such transactions may take place at any time with or without prior notice and may include, without limitation, entering into one or more privately negotiated acquisitions of additional shares of Common Stock, making a tender offer for some or all of the Common Stock, waging a proxy conte
st for control of the board of directors of the Issuer or taking other actions that could have the purpose or effect of directly or indirectly influencing control of the Issuer. Bio-Rad has engaged, and/or may in the future engage, legal and other advisors to assist it in evaluating strategic alternatives that are or may become available with respect to its holdings in the Issuer. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Except as set forth in this Statement, none of the Reporting Persons has any plan or proposals that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. </FONT></P>
<P align="center"> <FONT size=2 face="serif">Page 3 of 5 </FONT></P>
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<P>
  <B><I><FONT size=2 face="serif">Item 5. Interest in Securities of the Issuer. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">(a) Bio-Rad has acquired and, for the purpose of Rule 13d-3 promulgated under the Exchange Act, beneficially owns 665,639 shares of Common Stock, representing approximately 6.8% of the outstanding shares of Common Stock of the Issuer. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Except as set forth in this Item 5(a), none of Bio-Rad, and, to the best of its knowledge, any persons named in Schedule A hereto owns beneficially any shares of Common Stock. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">(b) Bio-Rad has sole power to vote and to dispose of 665,639 shares of Common Stock. </FONT></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">(c) Information concerning transactions in Common Stock during the past sixty days is set forth on Schedule B. </FONT></P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">(d) Inapplicable. </FONT></P>
<P>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">(e) Inapplicable. </FONT></P>
<P> <B><I><FONT size=2 face="serif">Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">To the best knowledge of Bio-Rad, there are no contracts, arrangements, understandings or relationships (legal or otherwise), between the persons enumerated in Item 2, and any other person, with respect to any securities of the Issuer, including any securities pledged or otherwise subject to a contingency the occurrence of which would give another person voting power or investment power over such securities other than standard default and similar provisions contained in loan agreements.</FONT></P>
<P> <B><I><FONT size=2 face="serif">Item 7. Material to be Filed as Exhibits. </FONT></I></B></P>
<P> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">Exhibit 1: Letter dated April 6, 2005 from Bio-Source to the board of directors of the Issuer. <br>
</FONT></P>
<P align="center"> <FONT size=2 face="serif">Page 4 of 5 </FONT></P>
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     <br>
          <B><FONT size=2 face="serif">SIGNATURE</FONT></B>
</div>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">After reasonable inquiry and to the best of
my knowledge and belief, I certify that the information set forth in this statement is true,
complete and correct. </FONT></P>

<br>
<br>
<DIV ALIGN=RIGHT><table width="45%"  border="0" cellspacing="0" cellpadding="0">
     <tr>
       <td colspan="2"><FONT size=2 face="serif">April 18, 2005</FONT></td>
     </tr>
     <tr>
          <td colspan="2"><hr noshade size=1 width=65% align=left>               </td>
     </tr>
     <tr>
          <td colspan="2"><font size=2 face="serif">Date</font></td>
     </tr>
     <tr>
          <td colspan="2">&nbsp;</td>
     </tr>
     <tr>
          <td colspan="2">&nbsp;</td>
     </tr>
     <tr>
          <td colspan="2"><FONT size=2 face="serif">/s/ Sanford S. Wadler </FONT></td>
     </tr>
     <tr>
          <td colspan="2"><hr noshade size=1 width=65% align=left>               </td>
     </tr>
     <tr>
          <td colspan="2"><font size=2 face="serif">Signature</font></td>
     </tr>
     <tr>
          <td colspan="2">&nbsp;</td>
     </tr>

     <tr>
          <td width="10%"><FONT size=2 face="serif">Name: </FONT></td>
          <td width="90%"><FONT size=2 face="serif">Sanford S. Wadler </FONT></td>
     </tr>
     <tr>
       <td><font size=2 face="serif">Title</font>: </td>
       <td><FONT size=2 face="serif">Vice President, General Counsel and Secretary</FONT></td>
     </tr>
</table>
</DIV>
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  <p>&nbsp;</p>
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  <p><FONT size=2 face="serif">Page 5 of 5 </FONT>
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<P align="right">
<B><FONT size=2 face="serif">EXHIBIT 1 </FONT></B></P>
<P align="right">
<U><FONT size=2 face="serif"><br>
CONFIDENTIAL</FONT></U><FONT size=2 face="serif"> </FONT></P>
<P align="left">
<FONT size=2 face="serif"><br>
April 6, 2005 </FONT></P>
<P>
<FONT size=2 face="serif"><br>
Jean-Pierre L. Conte<br>
Chairman of the Board<br>
BioSource International, Inc.<br>
542 Flynn Road<br>
Camarillo, California 93012 </FONT></P>
<P>
<FONT size=2 face="serif">Dear Mr. Conte: </FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">I am writing to affirm Bio-Rad&#146;s continued strong interest in acquiring BioSource and to propose an acquisition at a price of $8.50 per share in cash for each outstanding share that we do
not already own. Bio-Rad currently owns close to 5% of BioSource&#146;s outstanding shares.</FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">On multiple occasions over the last two years, including most recently on Monday, April 4, we have expressed our desire to acquire BioSource. Although you have often stated your intention to
sell BioSource at some point, on each of those occasions you have been unwilling to enter into merger negotiations with us or be specific on when you will initiate a sale process.</FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">We believe that the time for a sale is now and that our proposal will offer significant value to BioSource&#146;s stockholders&#151;value in excess of what BioSource has been able to achieve on
its own. Our proposal represents a 21% premium to the BioSource closing share price on April 5, 2005. Our proposal also looks very attractive when compared to BioSource&#146;s long-term stock price performance, representing a 30% premium to the
three-year average closing price.</FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">We believe that this proposal represents a full, fair and compelling value for BioSource, and would be extremely well received by your stockholders. </FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">In addition to the completion of customary due diligence, our proposal is conditioned on the negotiation of a mutually acceptable merger agreement. Our proposal has the full support of our
board of directors and management team and is not subject to any financing condition. We are prepared to move quickly toward the execution of definitive transaction documents. With your cooperation, we believe we can conduct due diligence and
negotiate a definitive merger agreement within two weeks. </FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">We are simultaneously sending you our proposal to nominate a slate of directors for election at your 2005 annual meeting. Although it is our strong preference to negotiate a mutually acceptable
merger agreement with BioSource, by delivering our proposal notice we are preserving our ability to pursue a proxy solicitation. </FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">This proposal sets forth our current intent with respect to the acquisition of BioSource and is not meant to be binding on you or us unless we enter into a definitive merger agreement.
</FONT></P>
<P>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">We are committed to acquiring BioSource and can move cooperatively and expeditiously to implement this transaction. We hope you will consider our proposal carefully. In light of the potential
significance to the stockholders of BioSource and Bio-Rad of the matters set forth in this letter, we are making this letter public. We stand ready to work together with you. </FONT></P>

<br>
<br>

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<TABLE width="95%" border=0 cellpadding=0 cellspacing=0>
<TR valign="bottom">
  <TD width=50% align=left>&nbsp;</TD>
  <TD colspan="2" align=left>
    <FONT size=2 face="serif">Very truly yours,</FONT>	</TD>
  </TR>
<TR>
  <TD width="50%">&nbsp;</TD>
  <TD width="5%">&nbsp;</TD>
	<TD width="45%">&nbsp;

	</TD>
</TR>
<TR valign="bottom">
  <TD width=50% align=left>&nbsp;</TD>
  <TD colspan="2" align=left>
    <FONT size=2 face="serif">BIO-RAD LABORATORIES, INC.</FONT>	</TD>
  </TR>
<TR>
  <TD width="50%">&nbsp;</TD>
  <TD width="5%">&nbsp;</TD>
	<TD width="45%">&nbsp;

	</TD>
</TR>
<TR>
  <TD width="50%">&nbsp;</TD>
  <TD width="5%">&nbsp;</TD>
	<TD width="45%">&nbsp;

	</TD>
</TR>
<TR valign="bottom">
  <TD width=50% align=left>&nbsp;</TD>
  <TD width=5% align=left><FONT size=2 face="serif">By:</FONT> </TD>
	<TD width=45% align=left> <FONT size=2 face="serif">/s/ Norman Schwartz</FONT>
</TD>
</TR>
<TR valign="bottom">
  <TD width=50% align=left>&nbsp;</TD>
  <TD width=5% align=left>&nbsp;</TD>
	<TD width=45% align=left> <FONT size=2 face="serif">Norman Schwartz</FONT>
	</TD>
</TR>
<TR valign="bottom">
  <TD width=50% align=right>&nbsp;</TD>
  <TD width=5% align=right>&nbsp;</TD>
	<TD width=45% align=right>
      <div align="left"><FONT size=2 face="serif">President and Chief Executive Officer</FONT>
	    </div></TD>
</TR>
</TABLE>
<BR>

<br>
<br>

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<p align="right"><br>
  <br>
<B><FONT size=2 face="serif">SCHEDULE A</FONT></B></p>
<p align="center"><B><FONT size=2 face="serif">DIRECTORS AND EXECUTIVE OFFICERS</FONT></B><BR>
    <B><FONT size=2 face="serif">OF BIO-RAD LABORATORIES, INC. </FONT></B></p>
<P> <FONT size=2 face="serif">The name, business address, title, present principal occupation or employment of each of the directors and executive officers of Bio-Rad Laboratories, Inc. (&#147;Buyer&#148;), are set forth below. If no business address is given the director&#146;s or officer&#146;s business address is 1000 Alfred Nobel Drive, Hercules, California 94547. Unless otherwise indicated, each occupation set forth opposite an individual&#146;s name refers to Buyer. All of the persons listed below are citizens of the United States of America. </FONT></P>
<TABLE width="100%" border=1 cellpadding=0 cellspacing=0>
  <TR valign="bottom">
    <TD width=50% align=center> <B><FONT size=1 face="serif">Name and Business Address</FONT></B> </TD>
    <TD width=50% align=center> <B><FONT size=1 face="serif">Present Principal Occupation Including Name and<br>
      Address<SUP>1</SUP> of Employer</FONT></B> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left> <I><FONT size=2 face="serif">Directors</FONT></I> </TD>
    <TD width=50% align=left>&nbsp;</TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">James J. Bennett</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Retired Chief Operating Officer and Executive<br>
      Vice President of Buyer</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Albert J. Hillmann</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Of Counsel to the law firm of Townsend and Townsend and Crew</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Ruediger Naumann-Etienne</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Owner and Managing Director of Intertec Group and Chairman of Quinton Cardiology Systems</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Philip L. Padou</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Retired Chief Financial Officer and Vice</FONT> <font size=2 face="serif">President of Ozier Perry and Associates</font> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Alice N. Schwartz</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Retired</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">David Schwartz</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Chairman of the Board of Buyer</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Norman Schwartz</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">President and Chief Executive Officer </FONT><FONT size=2 face="serif">of Buyer</FONT> </TD>
  </TR>
</TABLE>
<br>
<TABLE width="100%" border=1 cellpadding=0 cellspacing=0>
  <TR valign="bottom">
    <TD width=50% align=center valign="bottom"> <B><FONT size=1 face="serif">Name and Business Address</FONT></B></TD>
    <TD width=50% align=center> <B><FONT size=1 face="serif">Present Principal Occupation Including Name and</FONT></B> <br>
        <B><FONT size=1 face="serif">Address</FONT></B><B><SUP><FONT size=1 face="serif">1 </FONT></SUP></B><B><FONT size=1 face="serif">of Employer</FONT></B> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <I><FONT size=2 face="serif">Executive Officers<br>
      (Who Are Not Directors)</FONT></I> </TD>
    <TD width=50% align=left>&nbsp;</TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">John Goetz</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Vice President and Group Manager of Buyer</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Sanford S. Wadler</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Vice President, General Counsel and Secretary of</FONT> <font size=2 face="serif">Buyer</font> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Christine A. Tsingos</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Vice President and Chief Financial Officer of</FONT> <font size=2 face="serif">Buyer</font> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Bradford J. Crutchfield</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Vice President, Life Sciences, of Buyer</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Ronald W. Hutton</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Treasurer of Buyer</FONT> </TD>
  </TR>
  <TR valign="bottom">
    <TD width=50% align=left valign="top"> <FONT size=2 face="serif">Giovanni Magni</FONT> </TD>
    <TD width=50% align=left> <FONT size=2 face="serif">Vice President and International Sales Manager of</FONT> <font size=2 face="serif">Buyer</font> </TD>
  </TR>
</TABLE>
<HR NOSHADE SIZE=1 width=12% align=left>
<SUP><FONT size=2 face="serif">1 </FONT></SUP><FONT size=2 face="serif">Same address as director&#146; or officer&#146;s business address except where indicated.</FONT> <br>
<br>

<br>

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<p align="right"><br>
<B><FONT size=2 face="serif">SCHEDULE B </FONT></B></p>
<P align="center">
<B><FONT size=2 face="serif">TRANSACTIONS IN SHARES OF COMMON STOCK<br>
OF THE ISSUER BY BUYER DURING THE PAST SIXTY DAYS</FONT></B></P>
<P align="left">
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<FONT size=2 face="serif">All purchases of shares of Common Stock set forth below were made by Bio-Rad. </FONT></P>
<TABLE width="95%" border=0 cellpadding=0 cellspacing=0>
<TR valign="bottom">
	<TD width=18% align=center>
<B><FONT size=2 face="serif"> <B><FONT size=2 face="serif">Date of<br>
</FONT></B>Transaction</FONT></B>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center> <B><FONT size=2 face="serif"> <B><FONT size=2 face="serif">Number of Common<br>
	</FONT></B>Stock Purchased</FONT></B> </TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=20% align=center>
<B><FONT size=2 face="serif">Nature of Purchase</FONT></B>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<B><FONT size=2 face="serif">Price Per Share</FONT></B>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<B><FONT size=2 face="serif"> <B><FONT size=2 face="serif">Aggregate<br>
</FONT></B>Purchase Price</FONT></B>
	</TD>
</TR>
<TR>
	<TD width="18%">
<HR noshade size=1>
	</TD>
	<TD width="2%">
	</TD>
	<TD width="18%"><HR noshade size=1></TD>
	<TD width="2%">
	</TD>
	<TD width="20%">
<HR noshade size=1>
	</TD>
	<TD width="2%">
	</TD>
	<TD width="18%">
<HR noshade size=1>
	</TD>
	<TD width="2%">
	</TD>
	<TD width="18%"><HR noshade size=1>
	</TD>
</TR>
<TR valign="bottom">
	<TD width=18% align=center>
<FONT size=2 face="serif">3/15/2005</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">20,400</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=20% align=center>
<FONT size=2 face="serif">open market</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">6.93</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">141,410.76</FONT>
	</TD>
</TR>
<TR valign="bottom">
	<TD width=18% align=center>
<FONT size=2 face="serif">4/6/2005</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">13,390</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=20% align=center>
<FONT size=2 face="serif">open market</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">9.65</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">129,196.09</FONT>
	</TD>
</TR>
<TR valign="bottom">
	<TD width=18% align=center>
<FONT size=2 face="serif">4/8/2005</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">39,713</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=20% align=center>
<FONT size=2 face="serif">open market</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">9.50</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
<FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">377,150.79</FONT>
	</TD>
</TR>
<TR valign="bottom">
  <TD align=center><FONT size=2 face="serif">4/11/2005</FONT></TD>
  <TD>&nbsp;</TD>
  <TD align=center><FONT size=2 face="serif">103,315</FONT></TD>
  <TD>&nbsp;</TD>
  <TD align=center> <FONT size=2 face="serif">open market</FONT> </TD>
  <TD>&nbsp;</TD>
  <TD align=center> <FONT size=2 face="serif">$9.53</FONT></TD>
  <TD>&nbsp;</TD>
  <TD align=center><FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">984,622.95</FONT></TD>
</TR>
<TR valign="bottom">
	<TD width=18% align=center>
<FONT size=2 face="serif">4/18/2005</FONT>
	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center>
      <FONT size=2 face="serif">40,243</FONT></TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=20% align=center> <FONT size=2 face="serif">open market</FONT>

	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width=18% align=center> <FONT size=2 face="serif">$9.53</FONT>

	</TD>
	<TD width=2%>&nbsp;
	</TD>
	<TD width="18%" align=center><FONT size=2 face="serif">$</FONT><FONT size=2 face="serif">383,604.33</FONT></TD>
  </TR>
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