26O CARL R. MOORE. 



tilized, as Loeb has believed, 1 but that they are entirely un- 

 responsive to sperm, even though spermatozoa pass into the egg 

 substance. The present paper deals with an attempted analysis 

 of the conditions that are produced, after activation by hyper- 

 tonic sea-water, with reference to the capacity of the egg for 

 fertilization. 



Loeb 2 determined that an exposure to hypertonic sea-water 

 (50 c.c. sea-water + 8 c.c. 2\ m. NaCl) for a certain period of 

 time would cause sea-urchin eggs, after their return to normal 

 sea-water, to segment in quite a normal manner: they would 

 also undergo further developmental changes and become essen- 

 tially normal plutei. But certain eggs from the culture will not 

 have had a sufficiently optimum exposure to bring out their 

 full developmental tendencies and will as a result of this 

 remain quiescent after dividing into two, four or eight cells 

 Can these eggs activated by hypertonic sea-water yet be 

 fertilized by a spermatozoon? Loeb says they may be and uses 

 the assertion as a proof that the egg has not been changed in 

 its power of normal physiological reactivity; and that it may be 

 fertilized if only a spermatozoon reaches the cortex of the egg. 

 His hypothetical "lysin-like" substance contributed by the 

 spermatozoon can still assert itself by producing cytolysis and 

 his "corrective agent" of the spermatozoon may also act to 

 check the imposed cytolytic condition and allow the egg to go 

 on to development. 



If the conditions are as Loeb believes, we will naturally have 

 to assume that activation of the egg the initiation of develop- 

 ment is accompanied in the two instances: (i) in sperm activa- 

 tion and (2) in activation by artificial parthenogenesis, by a 

 different series of reactions that lead to the same end, namely 

 the production of swimming larvae. But if this is so we will 

 have to assume a lack of harmony in the development of an 

 egg when activated by different agents. In the vast number of 

 cases in which development may be artificially initiated there 

 is no common factor but the egg itself. Development is a series 

 of reactions on the part of the egg whether initiation is given by a 



iLoeb, '13. 



2 " Art. Par. and Pert.," pp. 237-238. 



