314 



HOMER W. SMITH AND G. H. A. CLOWES. 



TABLE I. 



NINE EXPERIMENTS ON THE INFLUENCE OF H-IoN CONCENTRATION ON 

 MATURATION OF Asterias EGGS. 



Per Cent. Permanently Immature. 

 pH 



Maturation is practically inhibited at pH 6.0, a point at which 

 normally fertilized Asterias eggs will grow quite normally, and 

 approximately the point at which the unfertilized egg retains its 

 viability for the longest time. It should be noted in Table I. that 

 the incidence of maturated eggs does not always increase uni- 

 formly with increasing alkalinity, but that in some experiments the 

 proportion of immature eggs falls to a low value on the acid side 

 of neutrality, rises noticeably at pH 7.0 (or 6.9) and then falls to 

 zero at 8.15. This irregularity in the influence of H-ion concen- 

 tration on the maturation process is not affected by washing sev- 

 eral times in the respective pH solutions. It appears, therefore, 

 to be attributable to alterations in the egg cortex rather than to 

 the activity of some substance in the supernatant fluid. 



THE INFLUENCE OF H-IoN CONCENTRATION ON Choetopteru* 



EGGS. 



The Chcetopterus egg differs from echinoderm eggs in that it 

 is activated by sea water to which HC1 has been added, as Loeb 

 showed many years ago. This activation, though not qualitatively 

 nor quantitatively sufficient to produce normal larvae, makes it 

 necessary to consider separately the consequences of exposing 

 the unfertilized egg to acid solutions, and the effects of such ex- 

 posures on subsequent fertilizability. 



Like the egg of Asterias, the Chcetopterus egg is a shed immature ; 

 though the germinal vesicle breaks down when the egg is placed in 



