144 CARR RICHARD MOORE. 



acid; membranes were counted by using the Leitz 7 mm. objec- 

 tive and ocular 3. Eggs were then transferred from vessel A 

 to vessel B containing 100 c.c. fresh sea water, carrying over 

 from 2 c.c. to 5 c.c. of the water from A. Immediately there 

 was added to B, 4 c.c. of a sperm suspension (2 drops dry sperm 

 + 100 c.c. sea water) freshly made up for the experiment. 

 Cleavages were counted about the 8 to i6-celled stage. The 

 approximate time of an entire experiment is one and one half 

 hours, but the time factor is neglible both as regards the length 

 of time the stock supply of eggs has remained standing and in 

 regard to possible deterioration of the sperm suspension. 



The following experiment was adapted to ascertain at what 

 stage, if any, in the action of the butyric acid, capacity for 

 fertilization was lost and to relate such results to the partheno- 

 genetic effect. The results during two summers have been 

 entirely consistent. 



Experiment 29, July 2j, 1915. 



Eggs after washing were divided into 16 lots. Each lot was 

 given a certain exposure to butyric acid (50 c.c. sea water 

 + 2.8 c c. n/io butyric acid), the action of acid checked by 

 transferring to alkali sea water, and eggs inseminated with sperm 

 in a dish of fresh sea water. 



These results are tabulated in a curve, Fig. i (a and b). The 

 axis of the ordinates represents the percentage of cleavages and 

 the axis of the abscissae the length of exposure to butyric acid 

 in seconds. 



In a first glance at such a table and curve four points are very 

 strikingly revealed to us: (i) The percentage of fertilization 

 decreases as the number of membranes increase. (2) After 

 membranes cease to appear there is a gradual rise in the per- 

 centage of cleavages: (3) From a longer exposure to butyric 

 acid cleavages again fall off until (4) after ten minutes' exposure 

 to butyric acid (varying in individual experiments) the fertiliza- 

 tion reaction is no longer induced by sperm. Let us look then 

 at the process of membrane production a little more closely. 



The concentration of the butyric acid in sea water used 

 Caused no visible change around the cortex of the egg following a 



