THE KANSAS UNIVERSITY SCIENCE BULLETIN. Vol. I, No. 8—September 1902. (Whole Series, Vol. XI, No. 8.) CONTENTS: THE SPERMATOCYTE DIVISIONS OF THE LOCUSTIDÆ, _C. E. McClung_. PUBLISHED BY THE UNIVERSITY, LAWRENCE, KAN. Price of this number, 50 cents. Entered at the post-office in Lawrence as second-class matter. KANSAS UNIVERSITY SCIENCE BULLETIN. VOL. I, NO. 8. SEPTEMBER, 1902. {WHOLE SERIES, {VOL. XI, NO. 8. THE SPERMATOCYTE DIVISIONS OF THE LOCUSTIDÆ. BY C. E. M’CLUNG. With Plates VII, VIII, IX, and X. I. INTRODUCTION. II. METHODS. III. NOMENCLATURE. IV. OBSERVATIONS. (a) General Structure and Form of the Testes. (b) The Spermatogonia. (c) The First Spermatocytes. (d) The Second Spermatocytes. (e) The Spermatids. V. COMPARISONS AND CONCLUSIONS. (a) Nomenclature. (b) The Spermatocytes of the Acrididæ and the Locustidæ. (c) Formation of the Tetrads. (d) The Spermatocyte Divisions. (e) The Accessory Chromosome. (f) Individuality of the Chromosomes. (g) Nucleoli. (h) Rest Stage. VI. SUMMARY. VII. BIBLIOGRAPHY. I. INTRODUCTION. Under the title, “A Peculiar Nuclear Element in the Male Reproductive Cells of Insects” (=16=), I published a preliminary account of the process characterizing the maturation divisions of the Locustidæ. This was of a general character and served merely as a basis for a description of the accessory chromosome in these cells. It is my present intention to give a detailed history of the spermatocyte divisions occurring in this family, after the manner followed previously in considering corresponding stages in the Acrididæ (=17=). Besides giving this account of processes, however, I shall be able to draw some comparisons between the two families. Eventually I hope to complete such a comparative study of all the Orthopteran families. Material for this larger investigation is now partially on hand, and is being added to as circumstances permit, so that it may be possible to carry through a study of the maturation stages in this order of insects within a few years. The value of comparative cytological study was urged by Vom Rath (=25=), and its importance in relation to the accessory chromosome and the maturation mitoses received recognition in both my earlier papers (=16=, =17=). Recently Montgomery (=15=) has added his influence to the movement.