BILATEEALITY IN CRYPTOBRANCHUS 363 



the spermatozoon; these changes were very clear and striking 

 in one spawning of eggs, though less obvious in others. The 

 internal phenomena alone are suft].cient to show that the sperma- 

 tozoon immediately exerts a very decided influence: a wave of 

 condensation of the cytoplasm and finer yolk globules always 

 marks the progress of the spermatozoon (Smith, 12, I, figs. 41 to 

 46). These features suggest that forces are at work comparable 

 to those that produce the gray crescent of the frog's egg. 



In order to investigate the relation of the entrance-path of 

 the spermatozoon to other features of the developing egg, an 

 attempt was made to control the direction of entrance of the 

 spermatozoon, as follows: Unfertilized eggs were taken from 

 the uterus of a ripe female, the accessory envelopes were 

 removed and each egg immersed in water in a separate Syracuse 

 watch-glass. Under these conditions the egg at once orients 

 itself with the animal pole uppermost. Each egg was then 

 fertihzed with milt applied by means of a fine pipette to the right 

 hand edge of the germinal disc or blastodisc. Great care was 

 exercised to guard against any subsequent change in the position 

 of the egg. The seminal fluid of Crypt obranchus is decidedly 

 viscous and difl5cult to handle in small quantities, consequently 

 the control of the direction of entrance of the spermatozoon 

 cannot be assumed to be very accurate. 



A number of circumstances combined to make the task of 

 carrying out of this experiment decidedly troublesome and labori- 

 ous. It was necessary to capture a large number of adult speci- 

 mens in order to get a few females whose eggs were in precisely 

 the right condition for fertiUzation. Less difficulty was experi- 

 enced in obtaining males in condition for breeding, nevertheless 

 some failures were due to the unripe or spent condition of the 

 males. The operation of removing the egg envelopes and apply- 

 ing the seminal fluid requires some time, and unless the eggs are 

 fertilized within a few minutes after their removal from the 

 uterus, they fail to develop. Of the eggs experimented upon 

 about 84 per cent either failed to develop or segmented in an 

 irregular and probably abnormal manner; very few reached the 

 gastrula stage. It is probable that this heavy loss was due in 



