40 RALPH S. LILLIE 



must also always be allowed for in lots of starfish eggs, which 

 show marked contrast to the regularity and uniformity of behav- 

 ior characteristic of Arbacia eggs. 



Since treatment with anesthetics and cyanide alone, without 

 preliminary membrane-formation, has typically no effect in initi- 

 ating the development of starfish eggs, while after the membranes 

 have been formed the same treatment greatly increases the pro- 

 portion of eggs that develop favorably, il is to be inferred that 

 the essential physiological effect of this treatment is of a kind 

 quite different from that of the initial membrane-forming treat- 

 ment. Expressed in general terms, the effect seems to be essen- 

 tially compensatory in nature, and consists in restoring a physio- 

 logically balanced condition which has been disturbed by the first 

 treatment. Thus if the initial action is cytolytic, the second is 

 probably anti-cytolytic. In these concentrations the above anes- 

 thetics and cyanide have in fact a protective or anti-cytolytic ac- 

 tion on eggs exposed to pure sodium chloride solution; and it 

 seems thus probably that the favorable effects of the after-treat- 

 ment depend on an action of essentially this nature — that is, 

 consist in a modification of the plasma-membrane of the oppo- 

 site kind to that produced by the primary or cytolytic treatment, 

 in other words, in the direction of a decrease of permeability, or 

 of an increase in the resistance to any permeability-increasing 

 conditions that may be present. 



Alcohols. After-treatment with alcohols gave results similar to 

 the above, but on the whole more favorable. This increased 

 favorability may however be due to the fact that most of the 

 experiments with alcohols were performed during late July and 

 August, at a time when the starfish eggs showed in general a 

 greater responsiveness to parthenogenetic treatment than in June, 

 in which month most of the experiments with the first group of 

 anesthetics were made. During late July and early August eggs 

 exposed to acid sea-water alone, without any after treatment, 

 often yielded a considerable and in a few cases a high proportion 

 of larvae. The effects of the after-treatment with alcohols are 

 shown in table 6, in which are summarized the results of four 

 series of experiments with both acetic and butyric acids, made on 

 four successive days toward the end of July. 



