284 BIOLOGY: GENERAL AND MEDICAL 



descend was already in being. But, as has already 

 been shown in discussing the theory in the chapter 

 dealing with the problems of inheritance, Weismann 

 was later obliged to modify the theory and to admit 

 that the germ plasm can and does become modified 

 through residence in its host. Such a conclusion was 

 inevitable; amphimixis, or the commingling of different 

 germ plasms, could never account for divergence, seeing 

 that originally the germ plasm was all the same. If the 

 germ plasm is susceptible of modification, as Weismann 

 himself admits and we must conclude, such modifica- 

 tions are undoubtedly governed by forces acting upon 

 the germ plasm while in the host, and hence probably by 

 conditions to which the host is subjected. This is per- 

 fectly in accord with Darwin and made Weismann one 

 of the strongest of the Neo-Darwinians. 



The Neo-Lamarckians, however, including Herbert 

 Spencer, Packard, Osborn, Eimer, among their early 

 champions, carried on a bitter warfare, and many inter- 

 esting phases of the subject were discussed during 1893 

 and 1894 in papers by Herbert Spencer on the one side 

 and Weismann on the other. 



The question at issue has never been settled. There 

 are present-day scientists who see no reason why natural 

 selection may not account for the origin of species, there 

 are others to whom it is totally inadequate. Indeed, 

 one scientist, Korschinsky, takes a diametrically opposed 

 view and appears as the most radical anti-Darwinian, 

 with the following expressions regarding natural selection: 



"The origin of new forms can only occur under conditions 

 favorable to them, and the more favorable such conditions are, 

 that is, the less severe the struggle for existence is, the more 

 energetic is their development. Under severe external conditions 

 new forms do not arise, or if they appear they are extinguished. 



"The struggle for existence, and the selection which goes hand 

 in hand with it, compose a factor which restricts new appearing 

 forms and restrains wider variations, and which is in no way 

 favorable to the production of new forms. It is, indeed, an inimical 

 factor in evolution. 



"Were there no struggle for existence, then there would be no 

 extinguishing of arising or already new forms. The organic world 



