21 



only time at which the receptacle is known to "be actively 

 secreting a suhstance is Just "before molting and it may simply 

 be a device for retaining the spermatophores at the molting 

 period. 



If a crah that has Just hegun to lay its eggs is opened 

 the lumen of the ovary and the oviduct will he found to he 

 full of eggs. Some eggs were taken from the lumen of the 

 ovary with a sterilized plpet and placed in filtered sea- 

 water. Since these developed into emhryoes it is evident 

 that fertilization takes place in the ovary. Sections were 

 made of eggs taken from the lumen of the ovary and from the 

 oviduct smd from these the phenomena of fertilization were 

 observed, hut we shall return to this later. 



VI. THE BEHAVIOR OP THE SPERMS. 



The sperms of this crah sure so very minute, the eggs so 

 relatively large and opaque, and the conditions for sperm en- 

 trance so difficult to reproduce on the microscopic slide, 

 I did not see the living sperm enter the egg. It is easy 

 however to interpret the structures seen in sections of eggs 

 taken at spawning time, after one has observed the behavior 

 of the spermatozoa under certain experimental conditions. We 

 shall proceed therefore to a description of this behavior. 



1. Methods of Study. 



Koltzoff '06, by his careful analysis of the effects on 

 the sperm of solutions differing in osmotic pressure, has 



