ADTHORS ABSTRACT OF THIS PAPER ISSUED 
Br THE BIBLIOGRAPHIC SERVICE, NOVEMBER 1 
SPERMATOGENESIS IN THE FLY, ASILUS SERICEUS 
SAYi 
CHARLES W. METZ and JOSE F. NONIDEZ 
f 
Station for Experimental Evolution, Carnegie Institution of Washington 
TWO PLATES (twenty-two FIGURES) 
CONTENTS 
Introduction 165 
Technique 167 
Topographical features 167 
Spermatogonia 168 
Final spermatogonial telophases 169 
Early growth period 170 
Later growth period 174 
The spermatocyte divisions 175 
The nucleolus 176 
Discussion 177 
Summarj^ 179 
Literature cited 180 
INTRODUCTION 
The rapid development of genetical studies on Drosophila in 
the last few years has drawn considerable interest to the subject 
of gametogenesis in the Diptera. The phenomena of mutation, 
crossing over, nondisjunction, etc., occur partly or wholly during 
gametogenesis, making it desirable that our knowledge of the 
latter be extended as far as possible. Another feature that has 
added interest to the subject is the characteristically 'paired 
association' of the somatic chromosomes of flies as distinguished 
from those of other animals. ^ It seemed possible that this pre- 
existent association of chromosomes in the soma and early germ 
cells might affect the processes of maturation in such a manner 
as to throw additional light on their significance. 
* We are indebted to Mr. C. W. Johnson for identifying the species used. 
2 For discussion of this phenomenon, see Metz, '16. 
165 
