*J7() SfHflu's III the /*/ii/siolof/i/ of FertUization 



Another experiiaeut was then made, on exactly the same lines as 

 the last, but in which the extract was made up of eight times the usual 

 strength. This experiment was made double, two different strengths 

 of sperm being used to each concentration of extract. The result was 

 exactly parallel to those of the preceding experiments. It is given in 

 Table Xy. 



TABLE XV. (+.24.6.) 



, I Wealier sperm 



Bid, B extract , _, 



I Stronser sperm. 



Finally the experiment was repeated with thick sperm. As was to 

 be expected, 100 "/ fertilized in water as in all the concentrations of 

 extract, but the sperm-halos round the eggs were progi-essively larger 

 in increasing concentrations of extract. 



Thus I cannot agree with Lillie's conclusion that the fertilizing 

 power of sperm which has stood in egg-extract is decreased. On the 

 contrary, the experiments just described, together with others recorded 

 in this paper, show clearly that treatment with egg-extract not only 

 has an immediate effect in increasing the fertilizing power of the sperm, 

 but suspensions in the presence of extract keep the power of being able 

 to fertilize more eggs than suspensions of the same sperm of the same 

 concentration in plain sea-water. 



V. Effects of Egg-waters on the Fertilizinc; Power of 



THE Sperm. 



The experiments described up to now have shown that a substance 

 or substances can be artificially liberated from the eggs — by breaking 

 them up in sea-water — which stimulates spermatozoa. It remains to 

 be seen whether or not such a substance is noi-nially secieted by the 

 eggs into the sea-water. If not, we have been dealing with a purely 

 artificial phenomenon, but if there is a normal secretion of a sperm- 

 stimulant by the eggs, its inv(>stigation must be of the highest im- 

 portance for the understanding nf the fertilization process. In the 

 experiments recorded below, eggs were allowed to remain in a relatively 

 small amount of water for some time, and this water was then used in 

 the same way as the extract had been in previous experiments. Such 

 sea-water, in which eggs have been allowed tn stand, I call "egg- water" 

 for the sake of brevity. 



