Adults aiul Ova 119 



The animals first submitted to infection died from blockage of vessels 

 by the growing worms before these had attained their full size. Such 

 hyperinfection was at first courted to establish the fact tliat the animals in 

 experimental use were actually susceptible. Later this had to be avoided 

 to ensure that the infected animals would survive sufficiently long to show 

 the effect of drug treatment on the worms in the portal system, and to give 

 the growing worms sufficient time to attain sexual maturity and produce 

 eggs whereby the specific character of the infection could be finally 

 identified. This proved a much more difficult task. Too slight an immer- 

 sion might result in a failure to infect or a failure to infect w^ith enough to 

 ensure the presence of females as well as males. Mishaps from all these 

 causes befell in the animals taken to England, and as will be seen, 

 necessitated a return to Egypt for further material. 



Before leaving for London, two or three eggs only were 

 Early seen. The first occurred in a female taken from themesen- 



Appearance of ^g^.y Q^ ^ ^^^Q^gg ^^^^j, j^^^ survived until June 24. The others 

 LATERA -.■ I < were seen a few days prior to sailing. These eggs were 

 lateral-spined and were the result of infection with cercariae 

 from P. hoissiji. According to Looss' theory these were the early abnormal 

 products of young sexually mature females of B. hcBmatohia ; according 

 to Sambon they should be regarded as characteristic ova of B. manaoni, 

 the cause of intestinal bilharziosis ; according to American parasitologists, 

 they were merely early abnormal products of B. licematohia, simulating 

 the true lateral-spined egg of B. mansoni, the cause of bilharziosis in the 

 New World. Males were present as well as females, but this fact had 

 now no significance, since Looss had himself abandoned the view that 

 the females produced eggs parthenogenetically. The females found had 

 only reached the egg-laying state. It was possible that they were just 

 entering Looss' " transition period." 



Sufficient time had not elapsed since the submission of animals to infec- 

 tion from Bullinus to warrant an examination of these prior to sailing. 



After reaching London, in July, animals continued, as before, to die 

 from hyperinfection with young adults. At the beginning of August, four 

 monkeys which it had been hoped would survive several months, began to 

 pass eggs and died within a fortnight of intense infection. These eggs 

 were lateral-spined. The cercariae used had been obtained from P. hoissyi. 

 No other type of egg was found. It could not be said, however, that the 

 worms had become mature sufficiently long to have passed through Looss' 

 "transition period." 



Certain of the rats which had survived until September 



ATER showed at post-mortem an extraordinary condition of the 



liver. This was enlarged and deeply pigmented with black 



amorphous granules. The surface was speckled with minute white spots. 



These were found to contain accumulations of lateral-spined eggs. The 



final peripheral veins were frequented by paired adult worms. The liver 



