CHAPTER II 



MERISTIC PHENOMENA 



Twenty years ago in describing the facts of Variation, argu- 

 ment was necessary to show that these phenomena had a special 

 value in the sciences of Zoology and Botany. This value is 

 now universally understood and appreciated. In spite however 

 of the general attention devoted to the study of Variation, and 

 the accumulation of material bearing on the problem, no satis- 

 factory or searching classification of the phenomena is possible. 

 The reason for this failure is that a real classification must pre- 

 suppose knowledge of the chemistry and physics of living things 

 which at present is quite beyond our reach. 



It is however becoming probable that if more knowledge of 

 the chemical and physical structure of organisms is to be at- 

 tained, the clue will be found through Genetics, and thus that 

 even in the uncoordinated accumulation of facts of Variation 

 we are providing the means of analysis applicable not only to 

 them, but to the problems of normality also. 



The only classification that we can yet institute with any 

 confidence among the phenomena of Variation is that which 

 distinguishes on the one hand variations in the processes of 

 division from variations in the nature of the substances divided. 



Variations in the processes of division are most often made 

 apparent by a change in the number of the parts, and are therefore 

 called Meristic Variations, while the changes in actual composition 

 of material are spoken of as Substantive Variations. The Me- 

 ristic Variations form on the whole a natural and fairly well 

 defined group, but the Substantive Variations are obviously 

 a heterogeneous assemblage. 



Though this distinction does not go very far, it is useful, 

 and in all probability fundamental. It is of value inasmuch as 

 it brings into prominence the distinct and peculiar part which 



31 



