20 THE GROWTH OF GROUPS 



being regarded by them a special property of that 

 variation which is of the body but not of the germ. If 

 we are to take this view of the case, we must admit 

 that in any population exhibiting fluctuating variation 

 in respect to a certain character, there must be a con- 

 siderable number of individuals which are capable of 

 transmitting their particular divergence to their offspring. 

 It is difficult to see clearly in such matters at present, but 

 at any rate we may be sure that very minute variations 

 may be inherited, while other more obvious ones are 

 not transmitted. It also seems to be true that the great 

 mass of variation within the species, the so-called indi- 

 vidual variation, is due to the varied distribution among 

 the species of characters such as may be called unob- 

 trusive ; characters which can never become obtrusive 

 or specific, owing to their very nature such cannot become 

 accumulated or built up into obtrusive or specific cha- 

 racters. 



7. There are certain attributes in animals which appear 

 to contrast with characters. It is necessary to qualify 

 this statement at some length by the following illustra- 

 tion in which characters are brought into contrast with 

 something which has been called " place variation." 



There is a large but unknown number of rats of a 

 certain kind living in the Eastern Himalayas and in 

 Java, each possessing a peculiar combination of characters, 

 peculiar in that the same combination does not occur in 

 any other kind of animal. They are spoken of collec- 

 tively as the species Mus jerdoni. If we wish to identify 

 a rat of this species, we must see if it contains this com- 

 bination of characters. The species may be described 

 briefly by comparison with the common brown Mus 



