11. 



In the other syr-icur>.* dishes the oiracidla must have 

 pnetrat<?d the young snails almost immediately ninoe they 

 were never to be found free in the water except for a few 

 minutes alt^r hatching* The penetration rf the young snail 

 by the iniracidium I was never fortunate enough to observe. 

 because rf its large anterior papilla which is capable of 

 bein/- T r^atly retracted and then forcibly extruded, I judge 

 that it would encounter little difficulty in piercing the 

 thin body wall of the viscera or even the more rigid foot of 

 the snail. 



From time tr, time, th^fe young snails were carefully 

 examined to see what at age followed. All the evidence 

 .;cint<? to the fait that the uiraoidla metamorphose directly 

 into r^liae, which in this paper I shall call mother-rediae. 

 ( n several occasions very small nio the r* rediae were obtained, 

 measuring in length froia 0.148 to 0*302 mm* After thirty - 

 five days in the tissues of the young onalls some mother- 

 rediae had only increased 0.028 mm. beyond the length of 

 the -jiracidiura, thus 5eing in all only 0.148 mm. long in 

 its most contracted condition. The smallest contracted free 

 daughter-redia ever s<?en measured 0.18C ram. in length, or 

 0.032 raia. longer thin mother-rediae when five weeVs old. It 

 these young me ther- rediae had been daughter-rediae instead 

 then there would aleo have been present large rediae, which 

 never were found even after the mo*?t careful examination. 

 Also if I had missed a generation, and these raother-rcdiae 

 were really daughter- rediae, then large numbers of daughter* 

 rediae should have been found, But nevr were more than three 

 found in a snail and that only once, the rest contained two 



