EGG-SECRETIONS OF ARBACIA AND ASTERIAS. 375 



color differences, the same results in tests, 2, 3, 4, 6, 7, 8, 9, 10, 

 n, 12, 13, and 14, were gotten with the Asterias secretion. 



III. THE SECRETION OF SUBSTANCES AT FERTILIZATION AND IN 



HYPERTONIC SEA-WATER. 



The unfertilized eggs of Arbacia show no noticeable decrease 

 in volume in sea-water even four hours after removal from the 

 ovaries ('I4 1 )- Fertilized eggs however are measurably smaller 

 in both Arbacia and Asterias within a few minutes after insemina- 

 tion ('i3 3 , 'I4 1 )- A change in the same sense seems also to occur 

 in the lamprey ('i4 2 ). 



The decreased volume is probably chiefly due to the loss of 

 water but it can be shown that in Arbacia other substances also 

 leave the egg. 1 



The first thing that occurs to one in testing whether at fer- 

 tilization more soluble substances are secreted than from un- 

 fertilized eggs, is to compare the agglutination strength of equal 

 quantities of sea water, with and without sperm, to which equal 

 quantities of unfertilized eggs have been added and allowed to 

 remain for equal lengths of time. Such experiments show that 

 there is more free agglutinin present in the sterile water. The 

 reason for this is not necessarily that the eggs at fertilization 

 secrete less of this substance, for Lillie has shown that the sperm 

 binds the agglutinin, a fact also indicated by the experiments on 

 re-activation without re-agglutination. Moreover it is quite 

 possible that at fertilization other substances are secreted and 

 combine with the agglutinin outside the egg. This alone or in 

 conjunction with the circumstance that a portion of the agglutinin 

 in these experiments would already be bound by the sperm in the 

 infected sea-water would account for the finding of a smaller 

 amount of free agglutinin by any subsequent agglutination test. 



1 McClendon ('09) says of Arbacia: "When the egg is fertilized or put in 'mem- 

 brane-forming' solutions a fluid is extruded which pushes the jelly out from the 

 surface of the egg." As neither the evidence for this statement, nor any reference 

 to the fact that something is also extruded from the unfertilized eggs, are given, 

 I do not know whether my contention is antedated or not. McClendon also states 

 that parthenogenetic reagents, when sufficiently concentrated cause the diffusion 

 of pigment from the eggs into the sea-water. If these concentrations are identical 

 with those most favorable for the initiation of cleavage, there is here an important 

 point of identity between the artificial and normal induction of development. 



