THE GROWTH OF GROUPS 49 



the same trap at Calicut and in a single individual at 

 Poona. 



This short list of peculiarities includes the most obvious 

 ones which were met with. They have been selected 

 because they have a certain resemblance to those which 

 are the distinguishing marks of certain established species, 

 known to taxonomists. 



Other peculiarities were noticed, but as they are 

 less like specific marks, they are of less importance for the 

 argument. Among these may be mentioned, white rats 

 and true albinos, yellow rats and tailless ones, such as 

 would be under an obvious disadvantage. Having 

 mentioned that rats showing these peculiarities are to 

 be found in India they doubtless occur in other countries 

 we must now consider how they are distributed among 

 the common kind. 



The representation is as follows : Rats with these 

 peculiarities are distributed in groups of varying magni- 

 tude among the normal mass; by magnitude is meant 

 numerical size, which may vary from two or three to 

 fifty or more. These groups will be referred to as family 

 groups. In regard to them the following, more or less 

 assumptive, statements will be made : 



(1) All the members of a group possess some obvious 

 feature or features which mark them off sharply from 

 their neighbours, the normal multitude. 



(2) The members of the group occupy a circumscribed 

 area, in the case of rats they occupy a single house or a 

 group of adjacent houses or a particular set of burrows 

 in a field. 



(3) A family group may contain from two to fifty or 

 more members, but we cannot draw a line between a 



E 



