MICHIGAN ACADEMY OF SCIENCE. 
97 
THE SPERMATOGENESIS OF AN ORTHOPTERON, CEUTHO- 
PHILUS LATEBRICOLA SCUDDER, WITH SPECIAL 
REFERENCE TO THE ACCESSORY 
CHROMOSOME. 
CRYSTAL THOMPSON. 
CONTENTS. 
I. 
II. 
III. 
IV. 
V. 
VI. 
Introduction. 
Material and methods. 
Observations, 
1. Structure of the testes. 
2. Spermatogonia. 
3. Growth period of the primary spermatocytes. 
4. Tetrad formation : division of primary spermatocytes. 
5. Division of secondary spermatocytes. 
6. Transformation of spermatids. 
Discussion and conclusions. 
Summary. 
Literature list. 
I. INTRODUCTION. 
Many studies have been made of Orthopteron spermatogenesis with 
reference to the accessory chromosome. The results embodied in this 
paper, though they do not add many new facts to those already ob- 
served, bring into line one more species and put forth additional proof 
of the presence of an accessory chromosome. This chromosome has 
been traced from the spermatogonia to a rather late stage in the trans- 
formation of the spermatid. For a discussion of the literature on insect 
spermatogenesis in general, and the spermatogenesis of Ihe Orthoptera 
in particular, the reader is referred to Davis (1908). 
The work here reported was begun at the Marine Biological Labora- 
tory’, Woods Hole, Mass., during the summer of 1909, under the direc- 
tion of Prof. T. H. Montgomery, Jr., and was carried on during the 
winter of 1909-1910 at the University of Michigan, under the direction 
of Dr. R. W. Hegner. I wish to thank both Prof. Montgomery and 
Dr. Hegner for their helpful suggestions and the interest they have 
taken in the work. 
•The author wishes to thank Mr. Bryant Walker and the Zoological Department of the University 
of Michigan for the opportunity of occupying a table at the Marine Biological Laboratory during the 
summer of 1909. 
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