SPERMATOGENESIS OF THE AMERICAN CRAYFISH, 

 CAMBARUS VIRILIS AND CAMBARUS IMMUNIS (?), 

 WITH SPECIAL REFERENCE TO SYNAPSIS AND 

 THE CHROMATOID BODIES 



NATHAN FASTEN 



From the Zoological Laboratories, University of Wisconsin 



ONE TEXT FIGURE AND TEN PLATES 



CONTENTS 



Material and methods 587 



Literature on the cytology of the decapod Crustacea 590 



The testis of Cambarus virilis 601 



1. Description of testis '. 601 



2. Variations in the testis throughout the year 602 



3. Zones of proliferation in the testis 604 



Spermatogenesis 604 



1. Spermatogonial stages 604 



2. First maturation stage 608 



a. The growth period, including synapsis and tetrad formation 608 



b. The chromatoid bodies 611 



c. The reduction division 611 



3. Second spermatocyte stage: Equation division 613 



4. Transformations of the spermatid to the spermatozoon 615 



5. Uncoiling of the mature spermatozoon 619 



6. Types of spermatozoa produced 620 



General considerations and conclusions ■. 621 



1. Synapsis and reduction of the chromosomes 621 



2. Summary 624 



Bibliography 627 



MATERIAL AND METHODS 



The following studies were made upon the testes of two species 

 of crayfish, Cambarus virihs and Cambarus immunis (?). Cam- 

 barus virilis was obtained in great abundance during the spring 

 and summer of 1912 and 1913. This species is very common in 

 the region about Madison, Wisconsin, and to it the writer devoted 



587 



JOURNAL OF MORPHOLOGY, VOL. 25, NO. 4 



