SPERMATOGENESIS OF AMERICAN CRAYFISH 601 



He says that although the spermatozoa of different species 

 of Astacus have been studied, a comparison of them soon shows 

 that they are dissimilar in appearance. Reinhard believes that 

 these differences are due to the different methods of fixation and 

 staining employed by the various investigators. 



In Astacus leptodactylus there are from eight to twenty 

 flagellated arms. The tail vesicle is round or barrel-shaped 

 in appearance and has openings at the proximal and distal ends. 

 The proxirrtal opening leads into a secondary depression of the 

 nucleus, where the central body lies. Here the central body 

 presents the appearance of a flat band instead of a vertical rod 

 SO common in other decapods. The walls of the vesicle are rather 

 thick and, when viewed from the side, they appear like two con- 

 cavo-convex lenses. It consists of chitin as was shown when the 

 spermatozoa were treated with cold or hot KOH. No explo- 

 sion of the vesicle was observed when the spermatozoon was 

 treated with concentrations of NaCl and other solutions for 

 many hours. 



THE TESTIS OF CAMBARUS VIRILIS 

 1 . Description of the testis 



The testis of Cambarus virilis (text fig. A), lies in the thoracic 

 region, directly below the cardiac chamber. It is a trilobed 

 organ, having two large oval lobes in the anterior portion of the 

 thorax (text fig. A, a.l.), while the third {md.), is situated pos- 

 teriorly in the median axis of the crayfish's body. Generally 

 the third lobe is approximately of the same shape and dimension 

 as the other two. Anteriorly this third testicular lobe becomes 

 thinned into a slender tubular portion, which runs forward and 

 joins with two similar slender tubules originating at the posterior 

 ends of the anterior lobes. Where these three slender tubules 

 join, the two vasa deferentia (text fig. A, v.d.) have their origin, 

 one on either side of the testis. Each vas deferens runs along 

 posteriorly within the thoracic cavity and, after coiling pro- 

 fusely, finally opens at the base of the last pair of walking legs. 



