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



In the Atlantic coast lobster, Homarus americanus, the proximal and 

 distal ends of the vas deferens differ both in size and general arrangement 

 of the inner epithelium. The proximal end of the tube (Fig. 21) shows a 

 more or less uniform layer of columnar epithelial cells (Fig. 21, e). In 

 one part of the duct these cells are slightly larger than in other regions 

 (See Fig. 21) and, also, some of them appear to bear short cilia. In the 

 center of the tube the spermatozoa (Fig. 21, s) may be seen surrounded 

 by the heavy, uniform fluid secretion (Fig. 21, /) manufactured by the 

 epithelial cells. 



The distal end of the vas deferens (Fig. 22) is very much larger in 

 size, and its lining epithelium bears fine types of cilia (Figs. 33-34, h). 

 Furthermore, this epithelium becomes highly convoluted in a number of 

 jDlaces (Fig. 23, e), thus affording a very much larger surface for the man- 

 ufacture of the milk-white secretions which also form the spermatophore 

 pouches (Fig. 22, g) around the spermatozoa. In the spaces between the 

 inwardly projecting epithelium of the convolutions a tunica propria (Fig. 

 23, p) may be seen. 



A careful study of the cells comprising the convoluted portions of 

 epithelium in the vas deferens of Homarus americanus shows that these 

 cells (Fig. 34) are very much longer than those forming the other uni- 

 form parts of the epithelium (Fig. 33). Furthermore, the cilia borne by 

 the former cells (Fig. 34, h) are much longer and coarser than those arising 

 from the latter cells (Fig. 33, h). Herrick (1909), who has studied the 

 male reproductive organs of the lobster, makes no mention of cilia in the 

 epithelium lining the vas deferens. In good preparations these cilia can be 

 distinctly seen projecting from the free borders of the epithelial cells, as 

 may be observed from the microphotographs (Figs. 33 and 34, h). 



In the spiny lobster, Panulirus interruptus, the vas deferens is very 

 long and contains a uniform inner layer of ciliated columnar epithelium 

 (Figs. 24 and 30, e). At one point in the tube this epithelial lining dips 

 inward (Fig. 24, i) and becomes profusely convoluted into a mass of sim- 

 ple tubular glands. Here, as in Homarus americanus, there is also a tunica 

 propria (Fig. 24, p) in the spaces between the convoluted epithelium. 



When the vas deferent tube of Panulirus interruptus is studied in its 

 entirety this convoluted glandular portion (Fig. 24, i) resembles a "typhlo- 

 sole-like" structure. Between it and the uniform layer of epithelium one 

 finds a heavy milky fluid secretion, in the midst of which lies a white wavy 

 and very much contorted membranous tube that contains the spermatozoa. 

 The contortions of this last mentioned tube appear in cross-sections as 

 open spaces (Fig. 24, g), and surrounding them may be seen the heavy 

 secretion (Fig. 24, /). When this secretion first comes out of the vas 



