744 Fluctuations 



selection of species complies as closely as possi- 

 ble with existing terminology, and does not 

 seem liable to any misunderstanding. 



It is a selection between species. Opposed to 

 it is the selection within the species. Manifest- 

 ly the first should precede the second, and if this 

 sequence is not conscientiously followed it will 

 result in confusion. This is evident when it 

 is considered that fluctuations can only appear 

 with their pure and normal type in pure strains, 

 and that each admixture of other units is liable 

 to be shown by the form of the curves. More- 

 over, selection chooses single individuals, and a 

 single plant, if it is not a hybrid, can scarcely 

 pertain to two different species. The first 

 choice therefore is apt to make the strain pure. 



In contrasting selection between species with 

 that within the species, of course elementary 

 species are meant, including varieties. The 

 terms would be of no consequence if only right- 

 ly understood. For the sake of clearness we 

 might designate the last named process with 

 the term of intra-specific selection, and it is 

 obvious that this term is applicable both to 

 natural and to artificial selection. 



Having previously dealt with species-selec- 

 tion at sufficient length, we may now confine our- 

 selves to the consideration of the intra-specific 



