28 FRANK R. LILLIE. 



for such eggs should fertilize without shaking, and this they fail 

 to do as the unshaken inseminated control shows. The eggs that 

 segment do not form a new membrane and they fail to develop 

 far ; in the loose type of cleavage and irregularity of development 

 they exhibit a weak condition. 



The rather significant fact will be noted in the tables that the 

 small percentages of segmenting eggs involved diminish in each 

 experiment with increased time of exposure : thus in Exp. 2 : 0.6 

 per cent, after 1^2 minutes exposure, < o.i per cent, after 2 

 minutes exposure; Exp. 3: 1.3 per cent, after i l / 2 minutes, 0.15 

 per cent, after 1^4 minutes, and 0.25 per cent, after 2 minutes 

 (the slight increase here is not significant, and is probably due to 

 sampling) ; Exp. 8: 0.3 per cent., 0.15 per cent, and o after i%, 

 i l /2 and 134 minutes respectively; Exp. 9: 4 per cent., 1.5 per 

 cent., 0.3 per cent, after 2, 2^4 and 2 l /2 minutes respectively. (In 

 Exp. 9 it will be noted in the protocol that membrane formation 

 was not very complete.) There is a tendency in each experiment 

 towards a vanishing point. This can mean only that each egg 

 tends towards an unfertilizable state under the conditions of the 

 experiment and that the small residuum shown in the experiments 

 is due to the statistical conditions of individual variation. 



In each experiment the eggs were very heavily inseminated, 

 i o to 20 times as much sperm being used as required for normal 

 fertilization. The spermatozoa did not, however, penetrate into 

 the experimental eggs except in rare cases, as shown by sections. 

 In those cases in which they were observed in sections to have 

 entered, apparently usually at points of injury to the egg-surface, 

 the spermatozoa remained unaltered in the cytoplasm. The yet 

 rarer cases in which a reaction resulting in cleavage was set up in 

 the egg were not observed in the sections, for the painstaking 

 search necessary to find them in such a mass of material did not 

 seem worth while. 



My results agree in principle with those of Moore and Just 

 and are in disaccord with those of Loeb. It will be noted from 

 the tables that the optimum time of exposure to butyric acid varies 

 considerably even at the same temperature with different lots of 



