SECURITIES AND EXCHANGE COMMISSION
                              Washington, DC 20549

                                  SCHEDULE 13G
                                 (Rule 13d-102)

       INFORMATION TO BE INCLUDED IN THE STATEMENTS FILED
       PURSUANT TO RULES 13d-1(b)(c), AND (d) AND AMENDMENTS THERETO
       FILED PURSUANT TO RULE 13d-2(b)

                                (Amendment No. 1)*

                                  Aerogen, Inc.
                -----------------------------------------------
                                (Name of Issuer)

                           Common Stock, $.001 par value
--------------------------------------------------------------------------------
                         (Title of Class of Securities)

                                    007779101
                               ------------------
                                 (CUSIP Number)

                               December 31, 2004
--------------------------------------------------------------------------------
            (Date of Event Which Requires Filing of this Statement)

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

[ ]     Rule 13d-1(b)
[X]     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).

                                  SCHEDULE 13G
CUSIP NO. 007779101                                                    2 of 6
_____________________________________________________________________________
1    NAMES OF REPORTING PERSONS
     I.R.S. IDENTIFICATION NOS. OF ABOVE PERSONS (Entities Only)

     Michael A. Roth and Brian J. Stark, as joint filers pursuant to

_____________________________________________________________________________
2    CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP       (a) [x]
                                                            (b) [ ]
_____________________________________________________________________________
3    SEC USE ONLY
_____________________________________________________________________________
4    CITIZENSHIP OR PLACE OF ORGANIZATION

     United States of America
_____________________________________________________________________________

NUMBER OF      5    SOLE VOTING POWER

SHARES              0
               ______________________________________________________________
BENEFICIALLY   6    SHARED VOTING POWER

OWNED BY            508,145 (See Item 4)
               ______________________________________________________________
EACH           7    SOLE DISPOSITIVE POWER

REPORTING           0
               ______________________________________________________________
PERSON         8    SHARED DISPOSITIVE POWER

WITH                508,145 (See Item 4)
_____________________________________________________________________________
9    AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON

     508,145 (See Item 4)
_____________________________________________________________________________
10   CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES
                                                                [x]
_____________________________________________________________________________
11   PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)

     9.9%
_____________________________________________________________________________
12   TYPE OF REPORTING PERSON*

     IN
_____________________________________________________________________________


                                  SCHEDULE 13G
CUSIP NO. 007779101                                                    3 of 6

Item 1(a).     Name of Issuer:

               Aerogen, Inc., a Delaware corporation (the "Issuer").

Item 1(b).     Address of Issuer's Principal Executive Offices:

               2071 Stierlin Court
               Mountain View, CA 94043

Items 2(a),
(b) and (c).   Name of Persons Filing, Address of Principal Business Office and
               Citizenship:

               This Amendment No. 1 to Schedule 13G is being filed on behalf of
               Michael A. Roth and Brian J. Stark, as joint filers
               (collectively, the "Reporting Persons").

               The Reporting Persons have entered into a Joint Filing Agreement,
               a copy of which is filed with this Amendment No. 1 to Schedule
               13G as Exhibit 1, pursuant to which the Reporting Persons have
               agreed to file this Amendment No. 1 to Schedule 13G jointly in
               accordance with the provisions of Rule 13d-1(k) of the Securities
               Exchange Act of 1934, as amended.

               The principal business office of the Reporting Persons is 3600
               South Lake Drive, St. Francis, WI 53235.

Item 2(d).     Title of Class of Securities:

               Common Stock, $.001 par value, of the Issuer (the "Common Stock")

Item 2(e).     CUSIP Number:

               007779101

Item 3.        Not applicable.

Item 4.        Ownership.

               (a)  Amount beneficially owned:

                    508,145 shares of Common Stock*

               (b)  Percent of class:

               Based on 4,884,829 shares of Common Stock outstanding as of
               November 5, 2004, (as set forth in the Issuer's 10-Q for the
               period ended September 30, 2004), the Reporting Persons hold
               approximately 9.9%* of the issued and outstanding Common Stock of
               the Issuer.

               (c)  Number of shares to which such Reporting Persons have:

                                  SCHEDULE 13G
CUSIP NO. 007779101                                                    4 of 6

                    (i)  Sole power to vote or direct the vote: 0

                    (ii) Shared power to vote or direct the vote: 508,145*

                    (iii) Sole power to dispose or to direct the disposition of:
                          0

                    (iv) Shared power to dispose of or direct the disposition
                         of: 508,145*

               *The Reporting Persons beneficially own an aggregate of 508,145
               shares of Common Stock. The foregoing amount of Common Stock and
               percentage ownership represent the combined indirect holdings of
               Michael A. Roth and Brian J. Stark. The shares of Common Stock
               reported in this Schedule 13G do not include certain shares of
               Common Stock issuable upon the exercise of warrants and
               conversion of certain preferred stock held by the Reporting
               Persons. Such warrants and preferred stock held by the Reporting
               Persons are subject to conversion caps that preclude the holder
               thereof from utilizing its exercise rights to the extent that it
               would beneficially own (determined in accordance with Section
               13(d) of the Securities Exchange Act of 1934 (the "Exchange
               Act")) in excess of 4.999% and 9.999% of the Common Stock, giving
               effect to such exercise.

               All of the foregoing represents an aggregate of 508,145 shares of
               Common Stock held directly by SF Capital Partners Ltd. ("SF
               Capital"). The Reporting Persons are the Managing Members of
               Stark Offshore Management, LLC ("Stark Offshore"), which acts as
               investment manager and has sole power to direct the management of
               SF Capital. Through Stark Offshore, the Reporting Persons possess
               voting and dispositive power over all of the foregoing shares.
               Therefore, for the purposes of Rule 13d-3 under the Exchange Act,
               the Reporting Persons may be deemed to be the beneficial owners
               of, but hereby disclaim such beneficial ownership of, the
               foregoing shares.

Item 5.        Ownership of Five Percent or Less of a Class.

               Not Applicable.

Item 6.        Ownership of More than Five Percent on Behalf of Another Person.

               Not Applicable.

Item 7.        Identification and Classification of the Subsidiary Which
               Acquired the Security Being Reported By the Parent Holding
               Company.

               Not Applicable.

Item 8.        Identification and Classification of Members of the Group.

               Not Applicable.

                                  SCHEDULE 13G
CUSIP NO. 007779101                                                    5 of 6

Item 9.        Notice of Dissolution of a Group.

               Not Applicable.

Item 10.       Certification.

               By signing below I certify that, to the best of my knowledge and
               belief, the securities referred to above 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.


                                  SCHEDULE 13G
CUSIP NO. 007779101                                                    6 of 6

                                   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 14, 2005

                                /s/ Michael A. Roth
                                -----------------------
                                Michael A. Roth


                                /s/ Brian J. Stark
                                -----------------------
                                Brian J. Stark


                                  SCHEDULE 13G
CUSIP NO. 007779101


                                                                       Exhibit 1

                             JOINT FILING AGREEMENT

     In accordance with Rule 13d 1(k) under the Securities Exchange Act of 1934,
as amended, the undersigned agree to the joint filing on behalf of each of them
of a statement on Schedule 13G (including amendments thereto) with respect to
508,145 shares of Common Stock, par value $0.001 per share, of Aerogen, Inc. and
further agree that this Joint Filing Agreement shall be included as an exhibit
to such joint filings.

     The undersigned further agree that each party hereto is responsible for the
timely filing of such Schedule 13G and any amendments thereto, and for the
completeness and accuracy of the information concerning such party contained
therein; provided, however, that no party is responsible for the completeness or
accuracy of the information concerning any other party making the filing, unless
such party knows or has reason to believe that such information is inaccurate.

          IN WITNESS WHEREOF, the parties have executed this Joint Filing
     Agreement on February 14, 2005.



                                /s/ Michael A. Roth
                                -----------------------
                                Michael A. Roth


                                /s/ Brian J. Stark
                                -----------------------
                                Brian J. Stark