STUDIES ON INSECT SPERMATOGENESIS. I. THE HISTORY OF THE CYTOPLASMIC COMPONENTS OF THE SPERM IN HEMIPTERA. ROBERT H. BOWEN. (From the Department of Zoology, Columbia University.) INTRODUCTION. No one who has noted the trend of cytological study during the last twenty years can fail to be impressed with the contrast between the progress that has been made in the analysis of the nucleus, and more particularly of the chromosomes, and the relatively doubtful outcome of parallel investigations on the cyto-plasm and its formed elements. Perhaps this is because no great, illuminating hypotheses have succeeded in doing for the cyto-plasmic structures what the theories of heredity and sex have accomplished for the chromosomes. At all events, it is evident that we are still on very uncertain ground in regard to many questions connected with the cytoplasmic constituents, especially such as relate to the physiology and reproduction of the cell. It is the purpose of this paper to deal with certain of these problems presented by the formed elements of the cytoplasm, more par-ticularly the mitochondria and the Golgi apparatus. In the case of the cytoplasmic structures, as in that of the chromosomes, the maturation period of the germ cells and the subsequent phenomena of fertilization offer the best setting for a study of many problems of the cell. Especially is this true of spermatogenesis, where the growth period of the spermatocytes and their subsequent division and differentiation into the sperms afford material for a critical study of a variety of cellular struc-tures. The activities of the various elements of the germ cells take on an added interest when one considers that the result is to be the formation of sperm which must carry the total hered-itary complex of the male, locked up with a mechanism for active 316
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