278 Studies in tlie Phtjuioloyi/ of Fertilization 



Eggs A were washed twice by allowing them to settle in finger- 

 bowls full of watt'r. They were then placed in a tube in 3 — 4 times 

 their volume of water. After 35 minutes, this water was drawn off 

 and a .second lot added to the eggs. When the latter had been in this 

 water for one hour, it was drawn off and used for the experiment. 

 Given amounts of sperm-suspension c (.see Table XVII) were added 

 to (1) 2 cc. plain sea-water, and (2) 2 cc. egg-watei-. To each of these 

 10 cc. of plain sea- water was added, and they \\i-\e poured on to separate 

 equal lots of eggs B. 



TABLE XVll. (1.2.5 ) 



I'lain water Kgg-wat«r 



„, , X t ^ drops sperm ... 35 89 



Blc ^egg.water ^ j,, ^^ ^ ^^ g^ ,,,j 



Thus Arbacia eggs behave as Ciona in secreting a substance into 

 the water, which increases the fertilizing power of the sperm of the 

 .same species. 



3. Experiments with Strongylocentrotus lividus. 



The four experiments given in Table XVIII were all made with the 

 same egg-water. Eggs were taken from three females and washed twice 

 to remove all coelomic fluid and ovarian tissue, by allowing them to 

 settle in finger-bowls full of water. They were then put in about five 

 times their volume of water, which was drawn off at varying intervals 

 (given in the Table) to be used for the experiments. 



Just before the fertilizations were made, given amounts of sperm- 

 suspension were added to (1) 2 cc. plain water, and (2) 2 ec. egg-water. 

 After 1 — 2 minutes 10 cc. plain water was added to each, and they were 

 then poured on to approximately equal lots of eggs. 



TABLE XVIII. (3.14.5.) 



Plain water Kgg-water 



„ , ,„ ,, . rr ■ , 1 3 drops sijerm 48 7H 



Exp. 1. Ah, t-gg-water 55 miuutes on eggs ' „„ ,„„ 



I 1 cc. sperm 97 100 



„.,,,,, L ^r- ■ L 1-5 drops sperm 45 58 



Exp. 2. Ale Lgg. water 65 m.nutes on eggs -j ^ ^^ ^^ J^ ^^ ^^^ 



„ ., ,, n ■ ,„/^ • . 1 3 drops speriii 18 30 



Exp. 3. A e. Egg-water 100 minutes on eggs ' 



' ' • be *'^ I 1 cc. sperm ... 5!» 84 



]-, . , ,^. T^ .,,<>■ i I 3 drops sperm 8 17 



Exp. 4. Ah, Egg-water I'iO minutes on ego-s-i , 



I 1 cc. sperm . . 3.j .53 



Table XVIII shows that the eggs of Strongylocentrotus give off a 

 substance, or substances, into the sea-water which stimulates the sperm 

 of the species in the same way as we saw the case for Civna and 

 Arhacia. 



