ACTIVATION OF STARFISH EGGS BY BUTYRIC ACID. 145 



themselves have no activating effect upon these eggs. Eggs 

 exposed on June 15 to sea-water at 8 and 10 for periods ranging 

 from 5 to 50 minutes showed no signs of activation. 



The rate of activation under the influence of low temperature 

 alone is very gradual. Out of eight additional series of experi- 

 ments with cold normal sea-water (i to 5), performed at differ- 

 ent times up to July 19, and in which the longest exposures were 

 respectively 4^, 8, 6, yf, 8, 7, 7, and 6 hours, only one yielded 

 any swimming larvae; in this series (July 2) about one per cent, 

 of the eggs formed blastulse after exposures to sea-water at i 

 to 3 for 7 hours (see Table VI). In the other series the only 

 evident effect was the formation of fertilization-membranes in a 

 variable proportion of eggs, followed by irregular changes of 

 form and breakdown; with the longer exposures a certain pro- 

 portion of eggs cleaved in some experiments, but none developed 

 further. 



It had previously been observed that the addition of alcohol 

 caused a decided acceleration of the activation-process in butyric 

 acid solution or warm sea-water. For example, in sea-water 

 containing 3 or 4 volumes per cent. C 2 H 5 OH the exposure to 

 .003 n butyric acid required to cause a majority of eggs to form 

 blastulse was shortened from 7 or 8 minutes to about 3 minutes. 1 

 This result suggested the possibility that the rate of activation at 

 low temperatures might similarly be increased by the presence 

 of alcohol. The experiments described in Table VI show that 

 this is the case. 



It is clear that activation at low temperatures as well as at 

 high temperatures is favored by the presence of alcohol. In 

 solutions of the above concentrations, alcohol, acting alone at 

 ordinary temperatures, has no evident effect; eggs exposed on 

 June 29 to 4 vols. per cent, alcohol at the three temperatures 

 1 8, 22, and 25, for periods ranging from 2 to 24 minutes, 

 showed neither membrane-formation nor development. The 

 favorable effect in the above series is thus due not to the direct 

 activating influence of the alcohol, but to a facilitation or acceler- 

 ation of the activation-reaction, which takes place spontaneously 

 though slowly at these low temperatures. It seems probable 



1 R. S. Lillie, Jour. Biol. Chem., loc. cit., p. 246, footnote. 



