UNITED STATES
              SECURITIES AND EXCHANGE COMMISSION
                    Washington, D.C.  20549


                          SCHEDULE 13G


            Under the Securities Exchange Act of 1934
                    (Amendment No. __2___)*

               Planet Polymer Technologies, Inc.
      ______________________________________________________
                        (Name of Issuer)

               Common Stock, $  No Par Value
      ______________________________________________________
                 (Title of Class of Securities)

                         727044109
               ____________________________________
                         (CUSIP Number)

                    December 31, 1999
     -------------------------------------------------------
     (Date of Event Which Requires Filing of this Statement)



Check the appropriate box to designate the rule pursuant to which
this Schedule is filed:

     -x--      Rule 13d-1(b)
     ----      Rule 13d-1(c)
     ----      Rule 13d-1(d)


*The remainder of this cover page shall be filled out for a
reporting person's initial filing on this form with respect to
the subject class of securities, and for any subsequent amendment
containing information which would alter the disclosures provided
in a prior cover page.

The information required in the remainder of this cover page
shall not be deemed to be "filed" for the purpose of Section 18
of the Securities Exchange Act of 1934 ("Act") or otherwise
subject to the liabilities of that section of the Act but shall
be subject to all other provisions of the Act (however, see the
Notes).






CUSIP No. 727044109                13G         Page  2   of   11
- ----------------------------------------------------------------
(1)  NAME OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

     Special Situations Private Equity Fund, L.P. ("SSPE")
      F13-3916551
     MG Advisers, L.L.C. ("MG") F13-3916549
- ----------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See
     Instructions)
  (a) | |
  (b) |X|
- ----------------------------------------------------------------
(3)  SEC USE ONLY
- ----------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION

     Delaware
- ----------------------------------------------------------------
 NUMBER OF     (5) SOLE VOTING POWER   See Marxe/Greenhouse
   SHARES       -------------------------------------------------
BENEFICIALLY   (6) SHARED VOTING POWER             None
 OWNED BY      -------------------------------------------------
   EACH        (7) SOLE DISPOSITIVE POWER  See Marxe/Greenhouse
 REPORTING     -------------------------------------------------
PERSON WITH:   (8) SHARED DISPOSITIVE POWER        None
- ----------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICALLY OWNED BY EACH REPORTING PERSON

  1,017,548 (includes 375,000 warrants and 449,000 cvt pfd)
- ----------------------------------------------------------------
(10) CHECK IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
     CERTAIN SHARES (See Instructions)

- ----------------------------------------------------------------
(11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     13.8
- ----------------------------------------------------------------
(12) TYPE OF REPORTING PERSON (See Instructions)

     IV/IA
- ----------------------------------------------------------------









CUSIP No. 727044109           13G             Page  3  of  11
- ----------------------------------------------------------------
(1)  NAME OF REPORTING PERSON
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (ENTITIES ONLY)

     Special Situations Cayman Fund, L.P. ("CAY") 98-0132442
     AWM Investment Comapny, Inc.  ("AWM") 11-3086452
- ----------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See
     Instructions)

  (a) | |
  (b) |X|
- ----------------------------------------------------------------
(3)  SEC USE ONLY

- ----------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION

     Cayman Islands/Delaware
- ----------------------------------------------------------------
 NUMBER OF     (5) SOLE VOTING POWER   See Marxe/Greenhouse
  SHARES       -------------------------------------------------
BENEFICIALLY   (6) SHARED VOTING POWER            None
 OWNED BY      -------------------------------------------------
   EACH        (7) SOLE DISPOSITIVE POWER  See Marxe/Greenhouse
 REPORTING     -------------------------------------------------
PERSON WITH:   (8) SHARED DISPOSITIVE POWER       None
- ----------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICALLY OWNED BY EACH REPORTING PERSON
     None
- ----------------------------------------------------------------
(10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
     CERTAIN SHARES (See Instructions)

- ----------------------------------------------------------------
(11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     None
- ----------------------------------------------------------------
(12) TYPE OF REPORTING PERSON*

     IV/IA
- ----------------------------------------------------------------










CUSIP No. 727044109             13G         Page  4  of  11
- ----------------------------------------------------------------
(1)  NAME OF REPORTING PERSON
     I.R.S. IDENTIFICATION NO. OF ABOVE PERSONS (ENTITIES ONLY).

     Austin W. Marxe
     David M. Greenhouse
- ----------------------------------------------------------------
(2)  CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP (See
     Instructions)

  (a) | |
  (b) |X|
- ----------------------------------------------------------------
(3)  SEC USE ONLY

- ----------------------------------------------------------------
(4)  CITIZENSHIP OR PLACE OF ORGANIZATION

     United States of America
- ----------------------------------------------------------------
 NUMBER OF     (5) SOLE VOTING POWER       1,017,548
  SHARES       -------------------------------------------------
BENEFICIALLY   (6) SHARED VOTING POWER           None
 OWNED BY      -------------------------------------------------
   EACH        (7) SOLE DISPOSITIVE POWER  1,017,548
 REPORTING     -------------------------------------------------
PERSON WITH:    (8) SHARED DISPOSITIVE POWER      None
- ----------------------------------------------------------------
(9)  AGGREGATE AMOUNT BENEFICALLY OWNED BY EACH REPORTING PERSON

    1,017,548 (includes 375,000 warrants and 449,000 cvt pfd)
- ----------------------------------------------------------------
(10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES
     CERTAIN SHARES (See Instructions)

- ----------------------------------------------------------------
(11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9

     13.8
- ----------------------------------------------------------------
(12) TYPE OF REPORTING PERSON*

     IN
- ----------------------------------------------------------------









                                        Page 5 of 11 Pages
Item 1.
(a)  Name of Issuer:  Planet Polymer Technologies, Inc.
(b)  Address of Issuer's Principal Executive Offices:
     9985 Businesspark Avenue., Ste A, San Diego, CA  92131
Item 2.
(a)  Name of Person Filing:  This statement is filed on behalf
of (i) Special Situations Private Equity Fund, L.P., a
Delaware limited partnership ("SSPE"); (ii) Special Situations
Cayman Fund, L.P. , a Cayman Islands limited partnership (the
"Cayman Fund"); (iii) MG Advisers, L.L.C., a New York limited
liability company,("MG"); (iv) AWM Investment Company, Inc., a
Delaware corporation ("AWM"); (v) Austin W. Marxe and (vi)
David Greenhouse.  Each of the foregoing is hereinafter
individually referred to as a "Reporting Person" and
collectively as the "Reporting Persons."
(b)  Address of Principal Business Office or, if none,
Residence:   The principal office and business address of the
Reporting Persons, other than the Cayman Fund, is 153 East 53
Street, New York, New York 10022.  The principal office and
business address of the Cayman Fund is c/o CIBC Bank and Trust
Company (Cayman) Limited, CIBC Bank Building, P.O. Box 694,
Grand Cayman, Cayman Islands,  British West Indies.
(c) Citizenship:  SSPE is a Delaware limited partnerships.
The Cayman Fund was formed under the laws of the Cayman
Islands. MG is a New York limited liability company and AWM is
a Delaware corporation.   Austin W. Marxe and David M.
Greenhouse are United States citizens.
                                   Page 6 of 11 Pages
The principal business of SSPE and the Cayman Fund
(individually, a "Fund" and, collectively, the "Funds") is to
invest in, sell, convey, transfer, exchange and otherwise
trade in principally equity and equity related securities.
The principal business of MG is to act as general partner of
and investment adviser to SSPE.   The principal business of
AWM is to act as the general partner of and the investment
adviser to the Cayman Fund.  MG and AWM are referred to
herein, individually, as an "Adviser" and, collectively, as
the "Advisers."   The principal occupation of Austin W. Marxe
and David Greenhouse is to serve as officers, directors and
members or principal shareholders of the Advisers.
2(d)      Title of Class of Securities: See cover sheets.
2(e)      CUSIP Number:  See cover sheets.
Item 3.   If this statement is filed pursuant to $240.13d-1(b)
          or 240.13d-2(b), check whether the person filing is
          a:
(a) ( )   Broker or Dealer registered under section 15 of the
          Act;
(b) ( )   Bank as defined in section 3(a) (6) of the Act;
(c) ( )   Insurance Company as defined in section 3(a) (19) of
          the Act;
(d) ( )   Investment Company registered under section 8 of the
          Investment Company Act of 1940;
(e) (x)   An Investment Adviser in accordance with $240.13d

                                   Page 7 of 11 Pages
          -1(b)(I)(ii)(E);
(f) ( )   An employee benefit plan or endowment fund in
          accordance with $240.13d-1(b)(I)(ii)(F);
(g) (x)   A parent holding company or control person in
          accordance with $240.13d-1(b)(1)(ii)(G);
(h) ( )   A savings association as defined in Section 3(b) of
          the Federal Deposit Insurance Act;
(i) ( )   A church plan that is excluded from the definition
          of an investment company under section 3(c)(14) of
          the Investment Company Act of 1940;
(j) ( )   Group, in accordance with $240.13d-1(b)(1)(ii)(J).
See Exhibit A attached hereto.
Item 4.   Ownership:
(a)  Amount Beneficially Owned: 1,017,948 shares of Common
Stock are beneficially owned by Austin W. Marxe and David
Greenhouse; of which 26,869 shares of common stock, 375,000
warrants and 449,000 convertible preferred are owned by SSPE.
The 375,000 warrants are exercisable for 462,444 common shares
and the 449,000 preferred are convertible into 528,235 common
shares.
(b)  Percent of Class:  13.8 percent of the Common Stock are
beneficially owned by Austin Marxe and David Greenhouse.  13.8
percent of the Common Stock are beneficially owned by SSPE and
No percent are beneficially owned by the Cayman Fund.


                                        Page 8 of 11 Pages
(c)  Number of Shares as to which the person has Rights to
 Vote and/or Dispose of Securities:  SSPE, MG, the Cayman Fund
and AWM have sole power to vote or to direct the vote and to
dispose or to direct the disposition of all securities
reported hereby which are respectively beneficially owned by
each Fund and its Adviser.    Austin Marxe and David
Greenhouse have shared power to vote or to direct the vote of
and to dispose or to direct the disposition of securities
reported hereby which are beneficially owned by Austin Marxe
and David Greenhouse by virtue of being Executive Officers of
the Investment Advisers.
Item 5. Ownership of Five Percent or Less of a Class:  If this
statement is being filed to report the fact that as of the
date hereof the reporting person has ceased to be the
beneficial owner of more that five percent of the class of
securities, check the following     .
Item 6.Ownership of More than Five Percent on Behalf of
Another Person:  SSPE and the Cayman Fund as owners of the
securities in question, have the right to receive any
dividends from, or proceeds from the sale of, such securities.
Item 7. Identification and Classification of the Subsidiary
Which Acquired the Security being Reported on By the Parent
Holding Company:  See Exhibit A attached hereto.
Item 8. Identification and Classification of Members of the
 Group:  Not applicable
Item 9. Notices of Dissolution of Group:  Not applicable.
                                   Page 9 of 11 Pages

Item 10.  Certification:
               By signing below I certify that, to the best of
my knowledge and belief, the securities referred to above were
acquired and are held in the ordinary course of business and
were not acquired and are not held for the purpose of or with
the effect of changing or influencing the control of the
issuer of the securities and were not acquired and are not
held in connection with or as a participant in any transaction
having that purpose or effect.
















                                   Page 10 of 11 Pages
                          SIGNATURE

     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.

Dated: February 29, 2000


               SPECIAL SITUATIONS PRIVATE EQUITY FUND, L.P.


               By:/s/ Austin W. Marxe
                  Austin W. Marxe
                  Managing Director

               MG ADVISERS, L.L.C.


               By:/s/ Austin W. Marxe
                   Austin W. Marxe
                   President and Chief Executive Officer

               SPECIAL SITUATIONS CAYMAN FUND, L.P.


               By: /s/ Austin W. Marxe
                   Austin W. Marxe
                   Managing Director


               AWM INVESTMENT COMPANY, INC.


               By: /s/ Austin W. Marxe
                   Austin W. Marxe
                   President and CEO



                    /s/ Austin W. Marxe
                    AUSTIN W. MARXE



                    /s/David M Greenhouse

                                   Page 11 of 11 Pages





                          EXHIBIT A


     This Exhibit explains the relationship between the
Reporting Persons.  MG Advisers, L.L.C. (MG), a New York
limited liability company, is the general partner of the
Special Situations Private Equity Fund, L.P., a Delaware
Limited Partnership.  AWM Investment Company, Inc., a Delaware
corporation, is the general partner of and investment adviser
to the Cayman Fund.  Austin W. Marxe and David M. Greenhouse
are the principal owners of MG and AWM and are principally
responsible for the selection, acquisition and disposition of
the portfolios securities by the investment advisers on behalf
of their Fund.