It was the purpose of the present investigation to determine if sensitivity to other antibiotics can likewise be affected by subjecting S. aureus to heparin contact. It is of special interest in this problem to determine whether heparin in some manner affects the combining process of penicillin with the cells of several strains of S. aureus.

In this study the effects of repeated antigen injections on total complement (C') and C'4 of guinea pig serum were investigated to determine if constant antigenic stimulation would show changes in the C' and C'4 titers. Attempts were also made to correlate any changes with variations in antibody titers during the repeated antigen injections.

The principal purpose of this work was to determine the effect of immunized guinea pig serum upon the survival time of tumor infected mice, and to make a correlation between this effect and the complement titer.

The current work was undertaken to test the ability of avidin to affect the course of leukemia when administered intraperitoneally.

It is the purpose of this paper to attempt to confirm the work of Schlagenhauf and Ingebrigsten and to show the effects of repeated injections of guinea pig serum immunized with various strains of mouse leukemia.

This thesis describes an attempt to increase the life span of mice after injection of a leukemic tumor. Fatty acids were used as a protecting agent against the leukemic tumor.