47. 



of the heavy infection of this snail with the cysts, 70.5 per 

 cent, I feel that the plan.". ria and ether forms r f animal 

 life play a minor role in the infection of the adult echinos- 

 tome host, 



The cyst wall in not hard or impervious to water as was 

 proved by Accident when 5*8 per cent snlt solution was used 

 instead of normal. In e-ich fin re ' **:Lthin three ninutes ever. 



_^, jt ^ 



cyst :-;nd of course ewery redia -md cerer-ri-v -;as dead. This 

 probably Tiein^ that the cyst is absorbing moisture all the 



time and possibly a small amount of food* r he cyst wall is 



although 

 round most of the time / ^ it is capable of being changed 



in shape ^li^htly, by the movement cf the enclosed agamo dig tome 



In order to discover how long cysts could live outside 

 the body of ^n-iils or in the tissue of dead snails, many 



specimens so infected were picked up at death, placed in 

 small ^laaa containers and examined from time to time. In the 

 handling cf the dead snails, the body will was often ruptured 

 and in thin manner freed eysta were obtained. The water in 

 the*e small glass containers "-sras not changed but mere water 

 3 ?dde^l ?s evaporation took pdace. If the water had been 

 changed occasionally, X feel sure -that the cysts would have 

 lived longer than they did because the bacteria and protozoa 

 infection would not have been so heavy. At the end cf ten 

 days every cyst appeared to be in a healthy condition. The 

 containers by this time had a very offensive odor. At the 



end of thirty -six days about 75 per cent of the cysts ^ere 



al tho ugh 

 alive, : in some cases -art of these showed signs of 



deterioration. At the end of forty -two days only- 11 per cent c 



he cysts wers^ Two days later only five per cent were alive. 

 /alive. /"5vi<iently the few remaining cysts would be <f*aa in a 



short time. Thus cysts in this crampt and unnatural condition 



