H. M. FucHS 275 



mixing, these were poured separately on to approximately equal amounts 

 of eggs. 



In the two experiments the fertilizing power of the sperm-suspension 

 decreased rather rapidly, both in water and extract, but at each suc- 

 ceeding fertilization more eggs were fertilized by the extract-sperm than 

 by the water-sperm. These experiments are a parallel to that recorded 

 in Table II for Ciona. 



F. R. Lillie (15, p. 558) states that " the powerful effect of the egg- 

 extract on spermatozoa of the same species may be shown by a complete 

 loss of motility, as we have already seen, and also by a cori'esponding 

 loss or diminution of the fertilizing power." He then describes an 

 experiment illustrating this. To five watch glasses containing each 

 eight drops of water oi- of different concentrations of egg-extract were 

 added thiee drops of " opalescent" sperm-suspension. After 12 minutes 

 " a th'op of a suspension of fresh eggs was added to each." 5 "/„ of the 

 eggs in the water segmented, but none of those in the four different 

 concentrations of extract. 



That this was quite contrary to my own results is clearly seen in 

 the experiments recorded in Table XIII. I determined, however, to 

 repeat exactly the experiment of Lillie's described above. I made the 

 fertilizations in the very small amounts of liquid which Lillie used, 

 although my preliminary trials had shown that this is an inaccurate 

 method, as, under these conditions, the eggs cannot be rapidlj' and 

 uniformly mixed in the different vessels. 



The details of the experiment are as follows. To each of four watch 

 glasses, containing respectively eight drops of water and eight drops of 

 difi'erent concentrations of extract as given in Table XIV, were added 

 three drops of a sperm-suspension. 12 minutes later, one drop of eggs 

 was added to each watch glass. Tw<i such experiments were made. 



TABLE XIV. (4.24.6.) 



5 drops water 3 drops water 

 8 drops water 3 drops extract 5 drops extract 8 drops extract 



Exp. 1. J/c, A extract <! 4 8 



Exp. 2. Ajd, B extract -5 13 35 .57 



Thus, in both experiments, treatment for 12 minutes in all three con- 

 centrations of egg-extract increased the fertilizing power of the sperm. 

 The most important points in which these two experiments differed 

 from that of Lillie quoted above, are the following: (1) Lillie's experi- 

 ments were made with Arhacia, mine with Strongylocentrotus; (2) Lillie's 

 extract was probably stronger: (3) I u.sed a weaker suspension of sperm. 



18—2 



