H. M. FrcHS 285 



unci (2) 10 CL-. Strongylocentrotus egg-extract. Each was then poured on 

 to approximately equal quantities of Ciona eggs. Each experiment was 

 made triple, three different strengths of sperm being used. 



In both experiments, involving six comparisons between the effects 

 of plain water and of the egg-extract on the fertilizing power of the 

 Giona sperm, the percentages of eggs fertilized were raised by treatment 

 with the extract. The results are especially marked in Exp. 2. 



5. Strongylocentrotus egg-water. 



The first experiment with Strongylocentrotus egg-water was made in 

 the same way as that with Arhacia egg-water recorded in Table XXIII. 

 Strongylocentrotus eggs (previously washed twice in finger-bowls of 

 water) were kept in little more than their own volume of water for "2^ 

 hours. Five drops oi' Ciona sperm-suspension b were added to (1) 1 cc. 

 normal sea-water, and (2) 1 cc. egg-water, containing Strongylocentrotus 

 eggs. 10 cc. of water was then added to (1) and to (2), and each was 

 poured on to separate equal amounts of Ciona eggs A (see Table XXVI). 



TABLE XXVI. (.3.5.30.4.) 



Egg-water containing 

 Water Sir'nioytoccnirMus eggs 



Cross, A/b ... 27 26 



The Table shows that the egg-water had practically no effect on 

 the fertilization percentages. The conditions of the experiment were the 

 same as those for the experiment shown in Table XXIII, in which the 

 Arhacia egg-water inhibited the fertilizing power of the Giona sperm. 

 That is to say, the egg- water was prepared by keeping the eggs for a 

 comparatively long time in a relatively small volume of water, and 

 Strongylocentrotus eggs were present in the sperm-suspension used to 

 effect the fertilization. At the time of fertilization the egg-water gave 

 a pink colour with a-Naphtholphthalein, in.stead of the green of normal 

 sea-water. 



For the reasons already given on p. 283 it was thought that 

 there was in this experiment some other factor influencing the Ciona 

 sperm than the Strongylocentrotus egg-secretion. A further series of 

 experiments was therefore made, in which the acidity of egg-water 

 which has stood for some time on a relatively large volume of eggs was 

 eliminated, and in which the egg-water used to influence the sperm did 

 not contain eggs. 



Eggs from two females of Strongylocentrotus were washed twice in 

 finger-bowls of watei-, after which they were placed in tubes with 4 — .5 



