OTTO GLASER. 



the probable acceleration of the oxidations due to the increase 

 in OH ions. I used the NaOH in conjunction with the egg 

 secretion on the theory that if the secretion affects the oxidations 

 it should antagonize the effect of the NaOH, since the secretion 

 alone, in the concentrations employed, retards the development. 

 As measured by the first three cleavages however, the effects 

 are not antagonistic, but additive, for the NaOH if anything had 

 an effect exactly the reverse of the expected and that actually 

 found for the later stages. This result is in harmony with Loeb's 

 later work. In his recent book ('i3 6 ), p. 35, he says: "The writer 

 published years ago a paper in which he showed that the develop- 

 ment of the eggs of Arbacia is retarded and finally inhibited if 

 increasing quantities of acid are added to the sea water. He has 

 since vainly attempted to show that the rate of development of 

 the sea urchin egg can be increased with the increase of the con- 

 centration of hydroxy lions in the sea water." If the reference 

 here is to the paper cited above, evidence is there given that the 

 increase in hydroyxlions does accelerate the development of Ar- 

 bacia, but this acceleration was not noticed clearly until the day 

 after fertilization. Both results seem really to be correct, only 

 the rate of cleavage is either not accelerated or even depressed, 

 whereas the rate of development from the blastula to the pluteus, 



is accelerated. 



TABLE I. 



RATES OF CLEAVAGE IN MINUTES AFTER INSEMINATION. 



