127 



The vagina runs straight from the pore to dorsal of the lateral canal 

 and testes. On transverse sections I find that on one side of the body 

 the cirrhus is dorsal to the vagina, on the other ventral to it. (The main 

 axis of these sections being uncertain, I cannot state which is right and 

 left.) Arrived in the median field it proceeds dorsally to the testes, but 

 ventrally to the vas deferens, forming a receptaculum seminis dorsal to the 

 most median testes. The receftaculum seminis is continued inwards by a 

 single canal, the fertilisation canal, which, however, soon branches, one 

 branch being the oviduct, the other the uterine duct. 



The ovary is single, somewhat bean-shaped. There is [as in 

 St. {globifunctata and ?) hefatica] neither vitelline gland nor shell gland. 

 The uterus at this stage forms a straight, cylindrical chamber, lying in 

 the transverse axis of the proglottis. At this stage the first eggs are 

 finding their way over into the uterus, so that it is evident that the testes 

 and the ovary ripen simultaneously ; in S. hepatica the ovary ripens before 

 the testes are quite mature. 



Spermatogenesis. 



The spermatogenesis is rather difficult to follow for several reasons. 

 In the first place it has to be studied on section series, then it is rather 

 confusing that several stages can occur at the same time in one and the 

 same testis, and finally one has to distinguish between the development 

 of two different kinds of cells, but which both appear to have a common 

 origin. 



As already remarked by Child (Amitosis in Moniezia), it is impossible 

 to distinguish the cells from which the testes arise from the parenchym 

 cells. The first stage at which one can feel certain is one at which two 

 or more cells are found lying together in definite arrangement and 

 apparently surrounded by a membrane. 



The youngest cells seen (urogenital cells, wall and basal cells) form a 

 syncytiium of four nuclei in a testicle — diameter of testicle, 9 /«; nucleus 

 6 i« X 4J i" cytoplasm stains blue ; nucleus blue, same depth of colour as 

 cytoplasm ; nucleolus minute, at the most 1 f^, very dark ; chromatin in 

 small round masses lying on the surface of the nucleus. The arrangement 

 of the nuclei not radial. 



On the same sections one finds testicles which have developed further, 

 and on which the division into the two mentioned types cells have taken 

 place. These can be classed by their appearance into " vellow " or acid 

 cells and blue or basal cells, according to their staining properties. The 

 " yellow " cells generally stain yellow with orange g, they are devoid of 

 cytoplasma or nearly so, a very large nucleolus, measuring up to 3 ^ (some- 

 times smaller in younger stages). The chromatin in young stages in 

 globules, later band-shaped, finally absent. The nucleolus in sections first 

 stained with borax carmine, then haematoxyhn and orange g, has a 



