278 NATHAN FASTEN. 



The smears were prepared in the usual manner, as described in 

 my earlier paper on the spermatogenesis of the edible crab, 

 Cancer magister Dana (Fasten, '18). Numerous fixatives were 

 tried, but Flemming's strong solution was found to yield the 

 best results. This mixture made the principal parts of the cell 

 stand out clearly. Furthermore, it produced some differentiation 

 in the staining capacities of the chromatoid bodies and the 

 chromosomes. The former invariably stained less heavily than 

 the latter. This was particularly noticeable when the slides 

 were considerably destained. As for staining, the best results 

 were obtained with Heidenhain's iron-alum haematoxylin and a 

 counter-stain of acid-fuchsin. 



The mature radial spermatozoa were studied in various 

 isotonic, hypotonic and hypertonic solutions in order to discover 

 the manner in which they function. These experiments have 

 already been published in a separate paper (Fasten, 1921) and 

 therefore the results will not be repeated here. 



DESCRIPTION OF MALE GONADS. 



The male reproductive organs of Loplwpanopeus bellus lie in 

 the cephalothoracic region. They consist of a bilobed tubular 

 testis and a pair of vas deferent ducts. Each lobe of the testis 

 runs laterally in the space between the heart and the digestive 

 glands. Directly below the anterior portion of the heart the 

 testicular lobes unite and from this junction point the convoluted 

 vas deferent ducts originate. These run posteriorly to the base 

 of the fifth pair of walking legs where they open to the outside. 



The male gonads attain their maximum size during the latter 

 part of June and the early portion of July. Between these 

 times the cells in the tubules of the testis are undergoing rapid 

 proliferation and all stages in the spermatogenesis process may 

 be secured. Typical cross-sections of the testis reveal a similar 

 picture to that given by me in 1918 for the edible crab, Cancer 

 magister Dana. Some of the tubules contain just one typical 

 stage; others show two distinct stages, while still others reveal 

 three steps in the maturation process. 



In the posterior region of the testis, where the lobes unite, and 

 in the vas deferent ducts are found the mature spermatozoa. In 

 Loplwpanopeus bellus, the mature spermatozoa within the distal 



