V20 Eejiort of the Bilharzia Mission in Egijpt, 1915 



from these cases was macerated and the eggs released iu enormous 

 numbers. Every described variation in size and shape of lateral-spined 

 egg was then found, but no terminal-spined eggs were seen. These animals 

 had been infected from P. boissyi. 



It had proved impossible to obtain material of the occasional large 

 cercaria in P. boissyi for experimental purposes, but it was anticipated that 

 in the very large series of infections made with cercarise from P. boissyi 

 for the experiments with drugs this cercaria would give evidence of its 

 presence. Neither in the eggs nor adults resulting, however, was any 

 indication seen of another species. The nature of this large cercaria 

 remained, therefore, a perplexing mystery. 



During September the animals submitted to very slight 



AiLURE OF infection were still alive and were anxiously watched for 

 liRST BuLlinus .J p fi-fi- AT " J 



„ evidence of successful mfection. No eggs were passed, 



XjXPERIAIENTS . 



and as the length of time that had now elapsed since 

 immersion was considered sufficient to allow of the worms attaining sexual 

 maturity, those treated with cercarise from Bullimis were killed and 

 examined. The results were disappointing. It was evident that in the 

 attempt to infect so slightly as to ensure the survival of the animals for 

 some months the number of cercarioe that had actually entered had not 

 been sufficient to ensure successful infection with paired adults. This 

 experiment was repeated with certain of the animals slightly infected with 

 cercarise from P. boissyi. No adult worms were found. 



Reviewing the position early in October, I realized that 



* the materials now available were insufficient to enable me 



c to deal effectively with the question of the zoological rela- 



tionship of the bilharzia worms that caused the symptoms 

 of vesical and intestinal bilharziosis. Certain facts might justify a reopen- 

 ing of the Sambon-Looss controversy, which had reached a position of 

 stalemate, but they would not render the final position taken by Looss 

 untenable. With the B. cercarim available, it was clear that a complete 

 solution was possible. The completion of this report was, therefore, post- 

 poned. I was granted permission to return to Egypt, and w^as enabled 

 to do so by the Committee of the London School of Tropical Medicine, 

 which allowed me to resume an unexpired portion of the Wandsworth 

 Research Scholarship, which I had previously held. 



Two series of experiments were seen to be required and were instigated 

 immediately after I reached Egypt in November : — 



(1) To lightly infect animals with P. boissyi cercariae so that they 

 would survive several months and thus enable the female bilharzia worms 

 to pass the " transition period." 



(2) To heavily infect animals with Bullimis cercarife to ensure a 

 successful diagnosis of the specific nature of this form. In view of the 

 successful and heavy infections that had followed the administration of 

 P. boissyi cercarife by the mouth, it v^as decided to niake the crucial experj- 



