508 Mr. 0. R. Narajaiia Rao on the Anatomy of 



of testis. The outer membrane can be easily removed by an 

 incision, and the contents are a large lobulated yellow testis, 

 in close contact with the rosette of tlie sperm-duct and 

 seminal cells in various stages of deveh)pment, together with 

 large oval ceils surrounded by a rich vascular plexus. In 

 the neiglibourliood of the testis are bundles of muscle-fibres, 

 which surround the mass of seminal cells, which thus 

 obliterate the cavity of the sac. The sperm mother-cells 

 and sperm morula lie outside tlie vascular plexuses, and 

 they, however, are richly granular and contain a large 

 centrally situated nucleus. In transverse sections of the sac 

 the seminal cells appear to be more centrally placed, being 

 surrounded by muscular fibres and, a very thick mass of 

 ovoid cells. The testis is seen attached to the anterior face 

 of the sac just in front of the funnel, the details of whose 

 cellular structure are better made out in teased preparations. 

 The funnel is certainl}^ a large opening, only a part of which 

 is, however, in contact with the testis, while the seminal 

 cells almost fill the other part of the funnel. The large oval 

 cells, which proliferate from the inner surface of the sac, 

 obviously act as unicellular organs for the storage of reserve 

 food-material. 



Though in point of size and form tiie testis-vesicles 

 of somite 10 differ from the anterior ones, yet in point of 

 histological structure there is absolute identity. The outer 

 wall of the sac in the case of the tubular vesicles is 

 excessively thin and almost non-cellular, and accordingly the 

 large oval cells enclosed in vascular plexuses show through, 

 giving the organs a smooth velvety appearance.. If xylol is 

 used for the clearing purposes, this cellular investment 

 easily comes off on applying needles for teasing, and the 

 testis in. each lobe is seen to form a tubular structure. 

 This tubular testis stands out, because of the investment of 

 circularly disposed muscular fibres. At the point where the 

 two testis-tubes open into the common rosette they become 

 continuous, and in the sac they are disposed in the form of 

 three ridges of large- hexagonal cells. The cavity, which is 

 trigonal, is filled with masses of sperms. The main point in 

 the structure of these curious sperm-vesicles is that the 

 cavity is lined by a layer of large spermatocytes, which 

 almost become continuous with the funnel-like expansion of 

 the vas deferens. There is no seminal funnel in somite 10 

 beyond the sac-wall of the testis, over the base of which, as 

 we have noticed, the vas deferens is continued as a sort of 

 outer tunic, which obviously represents the funnel. The 

 sperm-duct belonging to somite 9 is long and lies in a 



