Studies in Spermatogenesis (Part 1 of 2) by Nettie Maria Stevens

A brief account of a chromatin element resembling the accessory chromosome in Sagitta has been added for comparison. The spermatogenesis of each form will be described in detail, and a general discussion of the results and their relation to the accessory chromosome and sex determination will follow. The spermatogenesis of the aphid has been included in another paper, but a summary of results and a few figures will be given here for reference in the general discussion.