The sixteenth annual conference in the protein metabolism series sponsored by the Bureau of Biological Research, Rutgers University, represented the contributions of eight individuals. The conference was a departure from those preceding it in that no attempt was made to emphasize the relation of the subjects to proteins and protein metabolism. A diversity of papers was presented. Following the introductory remarks by T. von Brand, in which the general development of the field was outlined, L. R. Cleveland spoke of “Effects of insect hormones on the protozoa of Cryptocercus and termites.” J. D. Fulton presented a paper on “Some aspects of research on trypanosomes” followed by a discussion of “Factors influencing the rumen protozoa” by R. E. Hungate. Next, A. R. Timms presented a discussion on “Schistosome enzymes” followed by a paper on “Physiologic aspects of egg hatching and larval exsheathment in nematodes” by D. Fairbairn.