150 



in denying (p. 222) " any directly causal connection between 

 evolution and environment," there seems to be no recognition of 

 the fact that environment may operate directly upon the germ- 

 cells and cause variations, which, as MacDougal has experi- 

 mentally shown, are undoubtedly inherited. Again, in discuss- 

 ing " Differences in Growth-stages " (p. 237), no mention is 

 made of Diels' recent and very pertinent work on " Jungeiid- 

 formen tind Blutcnrcife ini PfiajizenreicJir Also no reference is 

 made to Blaringhem's work on the inheritance of the effect of 

 injuries, which surely has a bearing on environment as a causal 

 factor. 



One wonders if " Diversity of Normal Descent (Heterism) " 

 p. 244, et seq.) is offered as an original idea. Such seems 

 clearly to be the implication, and yet memory persists in recall- 

 ing Bailey's "The Survival of the Unlike,"* and his "Cross- 

 breeding and Hybridizing" (p. 5), to which no reference is made, 

 and the older " Bathmism " of Cope, and, to go still further back, 

 the clear statement of the idea by Herbert Spencer.f 



Here and there throughout the book the term " evolution " 

 seems to be used as synonymous with "organic evolution"; 

 e. g., " Evolution is a name for the process of gradual change by 

 which the diversity of organic nature has come about" (p. 284). 

 So, also, on page 277, quoted above. Furthermore, there seems 

 to be a redefinition of old terms, and then the employment of 

 these terms as newly defined when discussing Cookism, but as 

 previously defined when referring to other theories. For ex- 

 ample, on page 314, isolation, considered a factor in (organic) 

 evolution (old definition), is rejected as a factor in evolution (new 

 definition, /. e., variation through symbasis). From this the no7i 

 seqiiiter is inferred that the theories are wide apart. 



In referring to de Vries's theory of mutation, it is stated that 

 " Professor de Vries argues, in some of his writings, that muta- 

 tions are due to environmental causes," yet no reference is made 

 to the following statement of de Vries : " The variability of 

 species is independent of environment. In my experiments the 

 mother species mutates in all directions. . . . The mutation 



* See, e. g., pp. 20, 25, and 53 of that work. 

 I Principles of Biology 2 : 329. 1900. 



