castle: embryology of ClONA INTESTINALIS. 



209 



TABLE in. — Artificial Close Fektilization. 



Average for ten cases, 6% = proportion of 



TABLE IV. — Artificial Cross Fertilization. 



Average for five cases, 90% = proportion of 



eggs fertilized. 



As the animals employed in the above experiment had been confined 

 in the laboratory for some days, and the production of the sexual elements 

 had in consequence considerably diminished, it was thought desirable to 

 repeat tlie experiment on animals freshly collected. This accordingly 

 was done with tiie following equally conclusive results. 



TABLE III. a. — Artificial Close Fertilization. 



Average for ten cases, 9.4% = proportion of 

 eggs fertilized. 



TABLE IV. a. — Artificial Cross Fertilization. 

 100% fertilized in every case ! 



