1890.J 129 [Ryder. 



eggs were discovered by him, to expel only one polar body ; to make use 

 of this new fact in such a way as to make the expulsion of the second polar 

 body in perfectly sexual forms, remove a certain proportion of the ances- 

 tral germ-plasma, else, in time, the subdivisions of the ancestral plasmas 

 would ultimately be so great in number as to destroy, by repeated division, 

 the molecular integrity of the molecules representing such ancestral 

 plasmas. Unfortunately for such an hypothesis, Nature does not work 

 through foresight and does not anticipate such difficulties, and he is 

 unable to produce the slightest evidence that she does. Organisms do 

 not possess the power to foresee the remote consequences of their pro- 

 cesses ; they respond directly to conditions, or not at all. 



The logic of this argument of Weisrnann is exactly similar to that used 

 by Balfour in reference to the polar bodies in his "Comparative Embry- 

 ology " (i, p. 63), when he says "that the function of forming the polar 

 cells has been acquired by the ovum for the express purpose Of preventing 

 parthenogenesis." This implies that the egg possesses foresight of harm 

 coming to it through falling into a parthenogenetic habit ! And when 

 Weismann proceeds to elaborate his necessary hypothesis of a reduction 

 of ancestral germ-plasmas, and says "this must be so," he seems to for- 

 get altogether about the probably self-regulating physiological factors 

 controlling the dimensions of cells and their proportions of chromatin and 

 cytoplasm. 



The same difficulty was perceived in a somewhat different form and 

 very pointedly alluded to as fatal to the hypothesis of pangenesis, as early 

 as 1878, by Prof. J. Clerk-Maxwell, in his article, "Atom," in the third 

 volume of the " Encyclopaedia Britannica," p. 42. 



Lately, however, Platner's discovery that in Liparis dispar partheno- 

 genesis occurs with the extrusion of two polar globules, is sufficient to 

 render Weismann's hypothesis as to the significance of the second polar 

 body thoroughly untenable. 



There is clearly nothing left but to suppose that the polar bodies are an 

 expedient through which the egg returns to a condition of equilibrium 

 different from what it possessed prior to their expulsion. We have no 

 warrant whatever for assuming that this return is other than automatic 

 or comes from other than self-regulated impulses arising within the ovum. 

 Such impulses are very probably merely a manifestation of the attempt to 

 recur to and maintain a continuous process of growth, in the course of 

 which the production of polar bodies is only an incident. 



The physiological impulse from within which effects this equilibration 

 works, if my hypothesis has any value, as if certain parts of the egg 

 were to be excreted. In fact, if the hypothesis that the huge mass of 

 cytoplasm represented by an egg is a highly differentiated cell-product, 

 resulting from a very prolonged activity extending sometimes over many 

 months, or even years, of the nucleus and its chromatin, while the sper- 

 matic body is produced in a much shorter period, it must necessarily fol- 

 low that the controlling central nuclear body of th,e egg would undergo a 



PROC. AMER. PHILOS. SOC. XXVIII. 132. Q. PRINTED MAY 27, 1890. 



