AdiiJfs ami Ova 121 



ments by this method, which appeared to afford a more accurate means of 

 control in the dosage. To ensure longevity monkeys were used. Addi- 

 tional experiments were made by immersing rats and mice in infective 

 fluid, and other monkeys were subjected to skin infection. 



These new experiments proved, after the necessary lapse uf time, 

 completely successful. 



The smaller animals were killed week by week to watch the progress of 

 the development. Worms were first recovered from a mouse, infected by 

 immersion, on the seventeenth day. These were of course, very immature, 

 but they showed differences in the development of the gut from those 

 previously reared from P. hoissiji. This difference persisted during the 

 growth of the worms, as seen from later dissections, until the adult size 

 was almost reached. The two lateral branches of the gut failed to unite 

 early. In several of the experiments, males only were found. After five 

 weeks, males and immature females were recovered from the mesenteric 

 vessels of mice infected by immersion, but the numbers were small. A 

 mouse, injected subcutaneously with cercarioe obtained from B. chjhoicski, 

 by dissection showed eight adults, of which none were females, when killed 

 thirty-seven days later. In this series, worms were found after the sixth, 

 seventh and eighth week, but the females had not yet begun to lay eggs. 

 On the ninth week, however, the production of eggs had commenced. 



Turning to the series of infections by the mouth, the following contrast 

 is interesting : Two Indian monkeys, taken to Egypt from London for the 

 purpose of these experiments, were given infective fluid to drink on the 

 same day. The female monkey received fluid containing cercarife naturally 

 discharged by P. boissyi ; that administered to the male monkey contained 

 cercariae naturally discharged by Bullinus. The female monkey began to 

 pass lateral-spined eggs in the f<eces on the forty-second day, and died from 

 bilharzial dysentery on the sixtieth day. The male monkey showed no 

 eggs in fseces or urine on the forty-second day and was killed. Many 

 male and female worms were found in the liver and mesenteric vessels, 

 but no eggs were found either free or in the females. 



In the worms recovered from these older infections from BulUnns, the 

 lateral branches of the gut had now united, and a short caecum was 

 developing. The males showed a further point of difference from those 

 found in infections by P. boissyi, viz., the testes were less numerous, 

 numbering only four to five. As this number had been recorded for 

 S. hcematobinm, and was found to occur normally in B. bovis, it was still 

 impossible to say whether the Bullinus infection was due to the bovine or 

 the human parasite, without the evidence provided by the eggs. A further 

 monkey had meanwhile been infected from Bullinus by the niouth. This 

 passed numerous eggs in the twelfth week, and died of intense intestinal 

 bilharziosis five weeks later. No eggs were found in the urine nor were 

 any found in scrapings of the bladder wall. The eggs were terminal-spined 

 without exception and corresponded to those found in man, not those iu 



