Adults and Ova 131 



As the chief monographs on the anatomy of the adult bilharzia 

 \s-orms were based on materials collected in Egypt, such material quite 

 probably came from mixed infections. A comparison of the anatomy of 

 adults of B. mansoni from uncomplicated cases in the New World with 

 these published descriptions of B. hccmatobia was not likely to lead to 

 acceptable conclusions. 



It is evident then that a final settlement of the specific differences 

 between the adult worms of B. hcBmatohia and B. mansoni must be based 

 upon a comparison of specimens taken from cases of unmixed infection 

 and preferably from cases in South Africa and the West Indies respectively, 

 where such infections occur. 



The bilharzia worms that have been reared experimentally from 

 Bidlinus and Planorhis, unfortunately, do not attain in the laboratory 

 animals the full growth met with in their natural hosts. Although sexually 

 mature and actually producing eggs, the worms are still young and 

 small. Differential characters based upon measurements are likely to be 

 fallacious under these circumstances. Morphological differences, ma}^ 

 however, be relied on ; especially where these can be verified by reference 

 to full grown adults taken from the human body m unmixed cases of 

 vesical and intestinal bilharziosis. Unfortunately, an opportunity of 

 obtaining such material has not been forthcoming hitherto. The following 

 account of the differential characters as seen in experimentally reared 

 worms must be regarded as a purely tentative attempt to differentiate the 

 two species. It will be noticed, however, that it gains some extraneous 

 support in the observations on the anatomy of B. mansoni quoted above. 



In the males reared from Bidli)ius, the testes appear to number four or 

 five almost constantly. They are also of fairly large size. 



In males reared from Planorhis, the testes number seven to nine, and 

 appear to be relatively small. Differences between the two sets of males 

 are noticeable in the shape of the anterior portion bearing the suckers, 

 and the relative size of the suckers is probably also to be regarded as of 

 specific account. 



In females reared from Bidlinus, the eggs are constantly terminal- 

 spined, even in small young females. The ovary is smooth and situated 

 near the middle of the body. The lateral branches of the gut are lengthy 

 and the caecum correspondingly short. With this the range of the yolk 

 glands which surround the csecum throughout its length is apparently 

 short. 



In females reared horn Planorhis hoissyi the eggs are constantly lateral- 

 spined. Usually one, seldom two, and very rarely, four eggs, occur in 

 the uterus at one time. , This is due to the short length of the duct. The 

 lateral branches of the gut unite early, and there is a very long caecum. 

 The yolk glands surrounding the caecum have, therefore, a correspondingly 

 long range. The ovary lying in the fork made by the union of the gut 

 branches is elongated and is within a short distance of the uterine pore. 

 9* 



