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 				  EXHIBIT 31.02

CERTIFICATIONS

I, Kevin Perry, Chief Financial Officer of Demeter Management
Corporation (?Demeter?), the general partner of the registrant,
Dean Witter Principal Plus Fund, L.P., certify that:

1.	 I have reviewed this quarterly report on Form 10-Q of the
registrant;

2.	 Based on my knowledge, this report does not contain any untrue
statement of a material fact or omit to state a material fact
necessary to make the statements made, in light of the
circumstances under which such statements were made, not
misleading with respect to the period covered by this report;

3.	 Based on my knowledge, the financial statements, and other
financial information included in this report, fairly present
in all material respects the financial condition, results of
operations, and cash flows of the registrant as of, and for,
the periods presented in this report;

4.	 The registrant?s other certifying officer and I are responsible
for establishing and maintaining disclosure controls and
procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-
15(e)) and internal control over financial reporting (as define
din Exchange Act Rules 13a-15(f) and 15d-15(f)) for the
registrant and have:

   a)	Designed such disclosure controls and procedures, or caused
    	such disclosure controls and procedures to be designed
    	under our supervision, to ensure that material information
    	relating to the registrant, including its consolidated
    	subsidiaries, is made known to us by others within those
    	entities, particularly during the period in which this
    	report is being prepared;

   b)Designed such internal control over financial reporting, or
caused such internal control over financial reporting to be
designed under our supervision, to provide reasonable
assurance regarding the reliability of financial reporting and
the preparation of financial statements for external purposes
in accordance with generally accepted accounting principles;

   c)	Evaluated the effectiveness of the registrant?s disclosure
    	controls and procedures and presented in this report our
    	conclusions about the effectiveness of the disclosure
    	controls and procedures, as of the end of the period covered
    	by this report based on such evaluation; and
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   d)	Disclosed in this report any change in the registrant?s
    	internal control over financial reporting that occurred
    	during the registrant?s most recent fiscal quarter (the
    	registrant?s fourth fiscal quarter in the case of an annual
    	report) that has materially affected, or is reasonably
    	likely to materially affect, the registrant?s internal
    	control over financial reporting; and

5.	 The registrant?s other certifying officer and I have disclosed,
based on our most recent evaluation of internal control over
financial reporting, to the registrant?s auditors and the audit
committee of Demeter?s board of directors (or persons
performing the equivalent functions):

    a)All significant deficiencies and material weaknesses in the
 design or operation of internal control over financial
 reporting which are reasonably likely to adversely affect
 the registrant?s ability to record, process, summarize, and
 report financial information; and

   b)	Any fraud, whether or not material, that involves management
     or other employees who have a significant role in the
     registrant?s internal control over financial reporting.





Date:   August 15, 2005        /s/Kevin Perry
                                  Kevin Perry
                                  Chief Financial Officer,
                                  Demeter Management Corporation,
                                  general partner of the registrant