56 HARRIETT M. ALLYN. 



lack of oxygen not prohibitive of maturation, but it has been 

 determined that a solution of potassium cyanide, or the use of 

 sea-water de-aerated by boiling, actually stimulated the eggs to 

 form the polar bodies, and that, moreover, while the eggs were 

 still in the solutions. In Chtetopterus, then, may it not be that 

 maturation is a phenomenon concerned mainly with hydrolyses? 

 It seems to be generally agreed that hydrolyses can proceed in 

 lack of oxygen or in presence of potassium cyanide. The action 

 of cold used with potassium chloride is interesting in this con- 

 nection. The percentage of eggs forming polar bodies in this 

 case was greatly increased over the percentage of maturation 

 induced by potassium chloride alone. If cold suppresses oxida- 

 tive processes, this may be the reason for the increase in matura- 

 tion percentage. On the other hand, eggs subjected to the 

 action of heat do not form the polar bodies while in the warm 

 water, and in many cases the second polar body is never extruded, 

 even though development proceeds to the formation of swimming 

 larvae. Now if heat, as is generally supposed to be the case, 

 increases the rate of all reactions, it must increase both the 

 hydrolyses and the oxidations. Here, then, there should be a 

 stimulus to maturation, and this is in fact seen in certain eggs 

 which do form one or both polar bodies. But there is also either 

 an active suppression of maturation or a lack of stimulus to it in 

 the majority of eggs, for most of them form only one, or neither, 

 of the polar bodies. Where oxidations are increased, then, there 

 is a tendency to omit maturation. As another bit of evidence, 

 we may include the observation that an excess of oxygen used at 

 the same time with potassium chloride somewhat lessened the 

 percentage of swimmers, but used after potassium chloride, in- 

 creased it. Here again, apparently, excess of oxygen at the very 

 beginning of development is not good. The fact that oxygen- 

 saturated sea-water will induce a small percentage of eggs to 

 form polar bodies, may seem contradictory. But it is possible 

 that here we have a quite different set of reactions leading to some 

 of the same results. For example the oxygen excess may serve 

 to stimulate some reaction other than oxidation, only gradually 

 bringing about an increase in the oxidation rate. Thus it may 

 be that the reactions which are set in motion go on with a low 



