32 . SUMMAKY OF OUERENT RESEARCHES RELATING TO 



origin of species through the inheritance of acquired characters, according 

 to the laws of organic growth." 



It is not possible to summarize the concrete details of Prof. Eimer's 

 work ; the chief conclusions may be resumed as follows : — (1) Variations 

 are shown to occur along definite, determinate lines of development ; 

 not towards all points of the compass in arbitrary fashion, but in a few 

 directions, " as if on a determined plan." (2) The conditions of varia- 

 tion are found on the one hand in internal or constitutional changes, on 

 the other in environmental influences. The interaction of the external 

 forces and the physico-chemical changes of the growing organism is the 

 basis of variatioD. (3) As organisms progressively develope in accord- 

 ance with " the laws of organic growth," literally growing into their 

 places, species are but the stations in the progressive march. The same 

 laws hold good for the variations of the individual as for the establish- 

 ment of varieties and species. (4) " Constitutional impregnation " or 

 " conservative adaptation " is the organic result of persistence in a given 

 direction under similar conditions. (5) Variations due to environmental 

 influence are certainly transmissible, and may modify the organism so as 

 to originate new species without the help of Natural Selection. (6) Use 

 and disuse may similarly condition new characters, which persist without 

 Natural Selection. The latter has only a subordinate role ; growth and 

 the environment explain almost all. 



In his introduction, Prof. Eimer criticizes the Darwinian postulate 

 of indefinite variations ; emphasizes the deficiencies of an getiology 

 which does not discuss the primal conditions of variation, and maintains 

 that the utilitarian principle, which dijss not explain the origin of new 

 qualities, only partially at most accounts for their increase and domin- 

 ance. His observations, detailed in the body of the book, lead him to 

 conclude that " variations occur throughout in perfectly definite, and 

 only in a few directions, and are due to physico-chemical conditions in 

 the interaction between the material composition of the body and external 

 influences." 



The first chapter is chiefly occupied with criticisms of Weismann and 

 Nageli. In the second chapter the author enters into the heart of the 

 subject. The directions of variation are few and definite ; the new 

 characters, so to speak, crystallize out from the internal conditions of 

 growth, and may be useful, indifferent, or even hurtful. By " internal " 

 or better " constitutional " conditions, the author does not mean that 

 the causes of modification are to be found in a fundamental " vital force," 

 but simply in the physical and chemical processes involved in the very 

 composition of the organism. 



In opposition to Weismann and others, it is important to notice such 

 conclusions as the following, of which the concrete evidence must again 

 be left out: — " In my opinion the physical and chemical changes which 

 the organism experiences during its life through the influence of the 

 environment, and which it transmits, are the first conditions of modifica- 

 tion, and of the origin of species. From the material thus supplied, 

 the struggle for existence may select." 



All variations express themselves simply as growth. " Just because 

 the organic modification depends upon physico-chemical processes, the 

 result, as in the inorganic crystal, is definite," and can only express itself 

 in definite directions. " The origin of species follows exactly the same 

 laws as ordinary growth ; it is the consequence of unceasing variable 



