JO Art. 8. — S. Goto and Y. Matsudaira : 



stained cells opening by long ducts in groups into the lumen of the 

 ejaculatory duct. Corresponding to each group of these openings 

 there is a group of vesicles containing a granular substance project- 

 ing into the cavity of the duct; these are nothing else than the 

 secretions of the prostate glands, and since there are nearly as 

 many vesicles in the duct as there are gland cells outside it, the 

 former form an almost exact reflected picture of the latter. From" 

 the fact that these vesicles are found in nearly all examples we may 

 infer that the secretion of the prostate glands dissolves away only 

 very slowly in the ejaculatory duct. 



The penis is a dorsoventrally flattened, wide duct with a 

 thick wall, describing, when completely retracted, a round U 

 opening by its left end into the genital atrium and terminating 

 blindly at the other end. Where it overlaps with the ejaculatory 

 duct it lies on the ventral side of the latter, which opens into it 

 from the median side at a short distance from its blind termina- 

 tion (fig. 4). The lining cuticle, which is the direct continua- 

 tion of that of the genital atrium, is quite thick, and its free 

 surface is covered with very fine granules,., which assume in some 

 places the form of stiff-looking hairs. Outside the cuticle is a 

 layer of circular muscle fibres followed by one of longitudinal. 

 The thickness of the wall of the penis including the muscular coat 

 is about 12/jl. The penis is surrounded by numerous unicellular 

 glands similar to the prostate but staining less deeply and opening 

 in groups into the cavity of the penis. Their secretion does not 

 form vesicles like that of the prostate glands and is probably of a 

 sticky nature, covering the surface of the penis when it is everted 

 for copulation. The fine granules and stiff-looking hair-like struc- 

 tures mentioned above as occurring on the surface of the penis 

 cuticle are probably due to the presence of the secretion of these 

 glands, which may be called the penis glands. 



The penis sac is an oval muscular organ lightly flattened 

 dorsoventrally and enclosing the distal part of the ejaculatory duct 

 and the whole of the penis together with its numerous glands. 

 Its wall is formed by two well developed layers of muscles, an in- 

 ner of transverse and an outer of longitudinal fibres. The inter- 



