.596] SHORTER ARTICLES AXD DISCUSSION 



501 



importance of a gamete production, it is quite logical that the 

 cycle of development should close, but to state that the closing of 

 the cycle has brought about the production of the gametes, is 

 quite another thing. The acceptance of this would lead to the 

 inference that gametes arose in fresh or brackish water forms 

 where pronounced seasonal changes took place and not in larger 

 bodies of water like the ocean, the most probable place. 



The second deduction is a restatement of a conclusion reached 

 by Weismann (76) to the effect that amphimixis increases vari- 

 ability with the assumption that variations thus assumed to be 

 produced are inherited in a cumulative manner. The evidence, 

 however, available at present, supports a view directly contrary 

 to this, namely that the gametic condition makes evolution slower 

 by decreasing the diversity of available forms. Mendelian com- 

 binations— amphimutations — may occur but the result is a de- 

 crease in variability when the parental populations are compared 

 with the F, or with a succeeding generation. The amphimuta- 

 tions are transitory and there is no evidence that they present 

 anything actually new in themselves. 



Regardless of the opinions here at variance some of which can 

 only be established as sound generalizations through long experi- 

 mental investigation, the summary of gametogenesis by Pro- 

 fessor Coulter will be read with profit and pleasure by those in- 

 terested in problems of evolution as well as by those particularly 

 concerned with plant morphology and development. 



L. B. Walton 



Kenyon College, 



