THE GROWTH OF GROUPS 13 



A species is usually regarded as a number of like 

 animals ; the number, being indeterminable in almost 

 every case, is considered, perhaps for that reason, to be 

 infinitely great in every case. When therefore we find 

 a group containing so few individuals that the nunlber 

 of them can be determined, we say at once this is not a 

 species. 



The conception of species as groups, which are in- 

 variably infinite in their component numbers, is not a 

 true representation of nature and it hinders our under- 

 standing the origin of groups. There is no doubt that 

 groups, such as are called specific, are variable in the 

 number of their component individuals, and there is 

 little doubt that many of them are quite small in this 

 respect. 



THE TERM GROUP 



The word group appears in the title of this work 

 and will be found throughout the text. It is used in 

 place of the more usual terms species, sub-species, and 

 variety. Whatever meanings may be applied to these 

 terms it is evident that they are commonly used to 

 indicate groups of like animals, hence the term group 

 may be used instead of them. Set up any definition of 

 the term species, or of the term variety ; it will be possible 

 to find groups of like animals which do not satisfy the 

 requirements of either of those definitions. Take for 

 example a common definition of the term species. A 

 species is a group of animals which are fertile among 

 themselves but sterile with all others. Take also a common 

 definition of a variety as a kind of animal which is known 

 to have been derived from a species. Let us now turn 



