188 J. GRAHAM KERR. 



an abundant blood-supply to satisfy the needs of the glandular 

 epithelium. 



The Testis is, in its main morphological features, quite 

 similar to the ovary ; in other words, it is an invaginated area 

 of the lining of the coelom. Only in the testis great increase in 

 the area of the germinal epithelium has been brought about by 

 the involuted portion of ccelomic epithelium, instead of remain- 

 ing a simple sac, becoming divided up into a system of delicate 

 branched tubes. 



In an apparently adult specimen, the testis was a large 

 brownish organ of roughly triangular shape, its rounded apex 

 directed upwards and towards the right side. Its apical portion 

 was in close contact with the body-wall, while its basal part was 

 separated from the body-wall by the pericardium. 



The testis is slung up by a strong ligamentous band about 

 1 cm. broad to the tunic of the gizzard, by a similar but broader 

 band which is attached along a sagittal line to the body-wall 

 (the root of the siphuncle being about the middle of its line 

 of attachment), and finally along its anterior face by a thin 

 peritoneal fold to the loop of the intestine. Further, at its 

 lower end the epithelium covering the outer surface of the 

 testis is continued into that covering the pericardial septum 

 and heart. Near the inferior angle of the organ is its aperture — 

 a slit about 2 mm. in length, bounded by two flat, much 

 projecting lips, which, lying closely opposed to one another, 

 project into a deep recess covered by a crescentic flap, the 

 internal opening of the vas deferens. Thus, though the cavities 

 of the testis and of the vas deferens open quite independently 

 into the coelom, they are at least during sexual maturity 

 functionally continuous with one another. 



In a section through the testis of a young individual, the 

 aperture of the organ is seen to lead into a vestibule into which 

 open several straight ducts. Each of these, traced inwards, 

 divides up into numerous tubules which end blindly and are 

 aggregated into distinct lobes and lobules. Vestibule and tubes 

 are lined by epithelium continuous with that of the general 

 coelom. The wall of the organ is traversed by a sponge-work of 



