112 E. G. SPAULDING. 



to be explainable upon the basis of our theory and the usefulness 

 of the attempt to synthesize therewith demonstrated. 



From exactly this same standpoint also can the effect of an 

 entering spermatozoon be explained, whether its immediate action 

 be chemical or enzymatic, and thus the physical processes of 

 normal fertilization and segmentation made clear, at least in part. 



Clicinical Changes by ($) Physical Means. 



Theoretically possible physical means for producing this split- 

 ting of particles or of molecules are heat, and mechanical agita- 

 tion ; the former, as a rise in temperature, may be supposed to 

 have this direct effect in agreement with well-known phenomena 

 in pure chemistry, or, as a preliminary to this, to first make cer- 

 tain enzymes in the egg active ; or it may be considered to have 

 a purely physical effect, for since PV '= RT it directly increases 

 the pressure and decreases the tension. All of these three effects 

 may and probably do coexist. Agreeing with these theoretical 

 possibilities is the practical one of starting development in Arbacia 

 by the action of heat (rise in 7"). 



In the same way can also the practical method of causing par- 

 thenogenesis, e. g., in Asterias eggs by mechanical agitation, 1 be 

 explained, i. e., in analogy to facts in chemistry. For example, in 

 the " diazo-compounds " mechanical shock starts analytic proc- 

 esses. Such compounds are accordingly said to be " metastable." 

 At the same time that the pressure is increased by such analytic 

 processes the potential difference thus formed may be further 

 augmented by a decrease in the tension also caused by agitation, 

 as pointed out above. 



The effectiveness of this entire class of methods, both physical 

 and chemical, for causing analytic changes in the solute may be 

 explained as follows : Work is first done on the cell in strict ac- 

 cordance with the general physical principles stated. As a re- 

 sult of the analytic chemical processes taking place, the pressure 

 is at first increased, possibly also the tension decreased at the 

 same time. If the potential difference thus created is uncompen- 

 sated by a third, /. c., if the pressure of the surrounding medium 

 has been kept constant, c. g., by retransferring the eggs to sea 



1 Mathews, Am. Journal of Physiology, VI., 2, 1901. 



