36 KALPH S. LILLIE 



to be described are more favorable and in some cases exhibit a 

 close approach to the results of normal fertilization. 



Series II. Treatment with anesthetics after membrane-formation 



by fcCtty acids 



In this series the results of after-treatment with anesthetics 

 were more decidedly and uniformly favorable than in the series 

 with sodium chloride solution. The proportion of eggs forming 

 larvae after such treatment is almost invariably much higher 

 than after the simple membrane-formation with acid, although 

 to this rule also there are certain exceptions, the more significant 

 of which are considered below. Experiments with acetic acid 

 solution followed by anesthetics were performed last summer 

 with eighteen different lots of eggs at different times; in four of 

 these series butyric acid was also used, making a total of twenty- 

 two series of experiments with fatty acid. As a rule, starfish 

 eggs treated with acid alone, without after-treatment of any kind, 

 yield only a small proportion of larvae, rarely exceeding 10 per 

 cent; this was the case in twenty out of the twenty-two series; 

 in all of those series where the behavior of the control eggs was 

 normal (seventeen in all) the after-treatment led to a marked 

 increase in the proportion of favorably developing eggs, in some 

 cases eighty per cent or more of the eggs forming active blastulae. 

 In three series out of the twenty the eggs were unfavorable and 

 yielded only a few larvae after normal fertilization, and corre- 

 spondingly the proportion of parthenogenetically developing eggs 

 was small; in two out of these three series the after-treatment 

 with alcohol caused a definite though slight increase in the pro- 

 portion of larvae; in the third the increase was doubtful. The 

 remaining two series showed unusual behavior of a quite different 

 kind ; the eggs treated with fatty acid without any after-treatment 

 yielded a high proportion of larvae, and the after-treatment 

 appeared rather injurious than beneficial; these series will be 

 discussed more fully below. 



Last summer six series, of experiments were performed with 

 the solutions of table 4. Five of these series were carried out 

 within a single week toward the end of June, and the sixth a few 



