290 Puget Sound Marine Sta. Pub. Vol. 1, No. 26 



B. The Vasa Deferentia of Brachyura 



The Brachyura studied were Cancer magister, Cancer oregonetisis and 

 Lophopanopeus hellus. In these Brachyura the vas deferens is constructed 

 on virtually the same plan. There are three coats, ( 1 ) an outer thin 

 layer of fibrous connective tissue (Figs. 17-20, b), and (2) immediately 

 under this there is a thin circular layer of smooth muscle (Figs. 17-20, c), 

 while (3) the interior consists of a prominent layer of columnar epithelial 

 cells (Figs. 17-20, e), which contain huge nuclei. There is usually a dif- 

 ference in the epithelium of the proximal and distal ends of the duct. 



In the edible crab. Cancer magister, the proximal end of the vas def- 

 erens (Fig. 19) contains a very well developed layer of epithelium which 

 is convoluted (Fig. 19, e). The cells are greatly elongated, possessing 

 basal nuclei and numerous vacuoles distributed through the cytoplasm 

 (See Fig. 19). A careful examination of these cells shows that the vacuo- 

 les originate immediately below the nuclei, and that they then migrate 

 past them to the distal ends of the cells where they are dischargd into 

 the lumen of the vas deferens. In all probability these vacuoles are filled 

 with the secretion that helps to carry the spermatozoa down through the 

 duct and also functions in the formation of the spermatophores. The free 

 surface of these epithelial cells is thickened into a distinct cuticula (Fig. 



19, k), which under the high powers of the microscope is seen to contain 

 numerous short, stiff, vertical rods. Immediately below this cuticular 

 border terminal bars can be distinctly discerned. 



In Cancer oregonensis a similar condition to that just described pre- 

 vails in the proximal end of the vas deferens. In Lophopanopeus bellus 

 the epithelium in the proximal end of the vas deferens (Fig. 17, e) is not 

 convoluted but resembles that found in the distal end of the duct (Fig. 18, 

 e). Furthermore the lumen in the proximal end of the tube is very much 

 wider than in either Cancer magister or Cancer oregonensis (Compare 

 Figs. 17 and 19), and it also contains many mature spermatozoa (Fig. 

 17, s). 



The distal ends of all the crabs studied show the same general 

 structure. The tube itself as well as its lumen is very much larger in 

 this region (Compare Figs. 17 and 19 Avith Figs. 18 and 20). The epithe- 

 lial cells, however, except in Lophopanopeus bellus, are comparatively 

 smaller (Compare Figs. 19 and 20, e). In Lophopanopeus bellus the 

 epithelial cells of the distal and proximal ends are similar in appearance 

 (See Figs. 17-18, e). Within the lumen of the distal ends of these tubes of 

 Cancer magister and Cancer oregonensis numerous spermatophores (Fig. 



20, g) are seen suspended within the fluid secretions. In Lophopanopeus 



