H. M. FucHS 271 



test whether or not the drop of egg-extract necessarily introduced with 

 Sperm /S itself influences the fei-tilization, or whether Sperm /8 had 

 been altered by its treatment with extract. 



The experiments all agreed in showing that if two suspensions of 

 sperm from a given animal are made up of equal concentrations in 

 (a) water and (b) egg-extract, suspension (6) is capable of fertilizing 

 more eggs than is (a). The addition of a drop of extract to the eggs 

 at the same time as the sperm from the water-suspension (a) caused no 

 increase in the percentage of eggs fertilized (see column (2) of Table), 

 proving that the presence of this small quantity of extract at the 

 moment of fertilization was not reason for more eggs being fertilized 

 by (h). Evidently the sperm which had been treated with egg-extract 

 before being added to the eggs was stimulated in such a way that more 

 spermatozoa were capable of fertilizing eggs than was the case when 

 the sperm had previously been in sea- water alone. 



Two more experiments were made confirming the above conclusions. 

 In each case the sperm was treated, before being used to fertilize the 

 eggs, with different concentrations of egg-extract. Moreover, instead 

 of lying in the extract for half an hour before being used, as was the 

 case in the last experiments, the suspensions were added to the eggs 

 as soon as they had been well mixed by pouring. The results showed 

 that in the short time necessary for the latter operation, the sperm was 

 already stimulated. Increasing numbers of eggs were fertilized by 

 sperm from increasing strengths of extract. 



The details of the experiments are as follows : 



In Exp. 1 the sperm-suspension was made up and then three drops 

 were added to each of four dishes containing (1) 10 cc. sea-water, (2) 8 cc. 

 water -|- 2 cc. extract, (3) 4 cc. water -l- 6 cc. extract, (4) 10 cc. extract. 

 These four liquids, containing identical concentrations of sperm, were 

 poured on to four equal quantities of eggs in separate dishes. 



In Exp. 2, three drops of sperm-suspension were added to (1) 10 cc. 

 water, (2) 7 cc. water-|-3 cc. extract, (3) 10 cc. extract. These were 

 then poured on to three equal quantities of eggs. 



Table X gives the result of the experiments, which confirm those 

 of Table IX, and also show the effects of varying concentrations of 

 extract on the sperm. 



TABLE X. (34.16.4 and 34.21.4.) 



