DISTOMUM HAEMATOBIUM. 279 



these, however, appear to be little projections which give these 

 spots the appearance of a shagreened surface. The middle line 

 of the canal is free from these granules. 



The male sexual organs lie between the body and tail, behind 

 the ventral sucker. Here, where the two lateral margins double 

 downwards to form the canal, 5 — 6 roundish or oval organs are 

 perceptible, of which the 4 — -5 posterior are testicles, and closely 

 filled with delicate cells, whilst the foremost has transparent con- 

 tents ; its walls also exhibit double outlines, and pass in front and 

 beneath into an efferent duct, which opens freely externally, with 

 prominent lips. 



Bilharz detected no swarming of spermatozoa. 



With regard to the penis we know nothing, and it is also 

 unknown to us whether those asperities and granules occur only, 

 or in particular abundance, in those males which are embracing 

 their females, or whether they are only found in places where we 

 meet with sexually united animals. 



Description of the female. — The intestine, which is forked 

 before the ventral sucker, unites again posteriorly in the female 

 to form a large grayish-brown tubular sac, which winds about 

 down the middle line of the abdomen, and terminates in a csecal 

 extremity a little way from the end of the tail. This simple 

 portion of the intestine is surrounded on both sides up to its 

 furcate division by ramifications of the yelk-sacs, which at that 

 point unite into a single efferent duct. Here also lies the 

 germigenous organ with its delicate cells, which occur in the 

 other Trematoda, and from this a long, thin-walled oviduct, of 

 nearly equal diameter throughout, runs forward between the two 

 branches of the intestine ; it contains perfect eggs furnished with 

 germinal vesicles and shells, and opens at the hinder margin of 

 the ventral sucker. 



Eygs. — These are oval, strongly pointed towards one end, 

 which is always directed backwards in the uterus and oviduct, 

 and they occur in great quantities, and in every possible degree 

 of development. They have generally a delicate, thin membrane, 

 to which, as already observed, a pointed process is attached, and 

 they contain in their interior a transparent mass without distinct 

 outlines, but furnished with variously grouped small granules. 

 These eggs were found, as we shall shortly see, in the action of the 

 parasite upon the human subject, deposited in great masses, and 

 quite in heaps, on various parts of the inner surface of the intes- 



