264 BIOLOGY: GENERAL AND MEDICAL 



demand an infinite number. The existence of determinants, such 

 as Weismann conceived, is, as we have pointed out, a physical 

 impossibility, and this is equally so, were ten generations repre- 

 sented that would demand the presence in each chromosome of 

 more than one thousand separate orders of biophores. 



"Our way, then, lies between Scylla and Charybdis. Still, 

 between those two the cautious mariner could advance his craft 

 and, the gods helping, could achieve through the straits. And 

 here we would urge that our conception of the constitution of the 

 biophore affords us a proper equipment to achieve the passage. 

 We have, it will be remembered, been led onward to regard the 

 biophoric molecules as composed of a central body or ring^of nuclei 

 provided with side chains which are dissociated with the greatest 

 ease. As the environment has been modified, so have the side 

 chains undergone modification, and as these side chains become 

 utilized in the polymerization of the biophoric matter and the 

 formation of new biophores, so there has been a progressive in- 

 crease in the complexity of the biophoric molecule. 



" We have pointed out how, neglecting determinants, we must 

 regard the biophores in the somatic cells as undergoing extensive 

 modification when their environment has become altered, whereby 

 they have given rise to or controlled the different orders of cells in 

 the different tissues. As regards the germ cells, their biophores 

 must similarly be influenced, for it is upon their modification that 

 the whole evolution of living forms has depended. Clearly, the 

 biophores of the human ovum are vastly more complicated than 

 those of the amoeba or, again, than those of the lowest multicellular 

 organism of,the line of man's ascent, and yet the progressive elabora- 

 tion of the soma or body throughout the course of the ascent has 

 been the outcome of the germ plasm and the biophores of the 

 same within ovary and testis. 



"There are two or three possible causes for the progressive 

 variations of multicellular organisms: the mingling of the germ 

 plasms in conjugation (amphimixis), the effect of environment on 

 the respective germ plasms, and the effect of both of these com- 

 bined. The first of these was strenuously upheld for long by 

 Weismann as the controlling cause^ but he was compelled to 

 admit that the second must also be in action. In regard to this 

 second cause, we have demonstrated that it is clearly in action 

 in unicellular organisms that do not conjugate, as also in the 

 somatic cells of the highest multicellular forms of life; it is illogical 

 to deny its action upon the germ cells of the same. Not to waste 

 time by taking part in what has been an angry discussion, we are 

 prepared to accept the third course to admit that both the action 

 of external agencies and amphimixis are factors in variation, 

 retrogressive as well as progressive. 



" Granting this, and admitting that through the action of both 

 it comes to pass that the germinal biophores in no two members of 

 the same species are absolutely alike in constitution, what must 

 we conceive to be their action upon each other when, through 

 conjugation, biophores of two orders come together in the same 

 cell, the fertilized ovum? 



