STUDIES OF FERTILIZATION. 2Q 



eggs. Failure to take this into account may make considerable 

 difference in the results of superimposed insemination. The fact 

 that Loeb secured 20 per cent, of vigorous larvae in the principal 

 experiment that he cites suggests an under exposure, for the eggs 

 inseminated after the optimum exposure to butyric acid, that 

 segment, never develop normally. 



Conclusion. The membrane reaction after butyric acid treat- 

 ment is the same as after insemination ; this is shown by simi- 

 larity of the membranes formed in the two cases, and by the fact 

 that the rate of formation is the same. The result of rendering 

 the egg insusceptible to spermatozoa shows a possible slight 

 difference only, and this receives an obvious explanation on the 

 assumption that there is a variable tendency towards incomplete- 

 ness of reaction after butyric acid which in rare cases leaves some 

 of the reacting substances of the egg (fertilizin) free for sperm 

 action. 



EXP. 2. TEMPERATURE ESTIMATED 15-16 C. 



Membranes formed as follows after butyric : a, o ; b, o ; c. 85 per cent. ; 

 d, 99 per cent, (i per cent, without) ; e, 99 per cent, (optimum) ; /, 99 per cent, 

 (some imperfect) ; g, 99 per cent, (imperfect) ; h, 99 per cent, (imperfect). 



It is doubtful if any membranes were destroyed by shaking 15 minutes 

 after their formation (a, b, c). In d 75 per cent, of the membranes were 

 destroyed. 



i These represent a sample of the same lot of eggs tested two hours later 

 than all other items of this experiment. 



