STUDIES IN ARTIFICIAL PARTHENOGENESIS. l8l 



brane swelling when 5 drops were added to 25 c.c. of sea-water, 

 but only a moderate per cent, of fertilization when i drop was 

 added to 25 c.c. of sea-water containing eggs. In the main 

 experiment 3 drops of watery "dry" sperm were added to approx- 

 imately 10 c.c. of sea-water, and the resulting suspension was 

 the one used. Two Syracuse watch-crystals were employed. 

 \Yntch-crystal A contained 4 c.c. of sea-water plus I c.c. of 

 filtered blood (from 9s). Watch-crystal B contained 5 c.c. 

 of sea-water and no blood. 8 drops of a dilute egg suspension 

 were then added to A and to B (at n 115^ A.M.) and two min- 

 utes later, 2 drops of the sterm suspension just mentioned, 

 were added. At II :2O, eggs in B (i. e., in the absence of blood) 

 all had membranes widely swollen all around. At 11:22, the 

 eggs in A were examined. Most of the eggs showed not a trace 

 of cortical change, but some showed membrane elevation. Short- 

 ly after, a count was made of eggs in A. It was found that 

 23 showed no cortical change, I was doubtful, it may have had 

 a swollen membrane, 9 evidently possessed elevated membranes. 



Thus the presence of blood prevents membrane swelling, 

 and as one result of this prevention of excessive swelling, mem- 

 brane elevation is possible, although without blood it could 

 not have been produced. In this experiment, the anti-swelling 

 effect of blood towards sperm suspension is conclusively demon- 

 strated, for the blood evidently does not prevent access of sperm. 1 



The fact that the presence of blood inhibits membrane swelling 

 in concentrated sperm suspensions, indicates that the swelling 

 is produced by an acid. As is well known, all spermatozoa are 

 abundantly provided with nucleic acid, and 'it is very probable 

 that a nucleic acid or its derivative is responsible for the swelling. 



I have tried a number of times to watch the process of normal 

 membrane elevation under high power, but with only scant 

 success. The presence of a coverslip produces difficulties. If a 

 drop of egg suspension is placed on each of two slides, and one 



1 The further history of the eggs in this experiment is very interesting. On 

 September 2, there are considerably fewer larvae in A (where blood was present) 

 than in B. But whereas all of the larvae in A have well-marked arms, none of the 

 larvae in B possess even the suggestion of arms. On September 3, the larvae in B 

 are still perfectly armless, whereas those in A have the usual long arms of the 

 pluteus stage 



