THE GROWTH OF GROUPS 73 



house after house until they came to rest in the centre of 

 the city and commenced to breed. If we supposed that 

 they arrived there in a corn sack, or by any other means 

 of transport, the difficulty is not lessened, for we do not 

 know whencesoever they can have come originally. 

 The relative distribution of the whole-coloured and white- 

 bellied kinds is known in India and lends no support 

 whatever to the theory of migration. If we knew that 

 there was one extensive area inhabited by the white- 

 bellied kind we could imagine that an occasional isolated 

 body of them, occurring elsewhere among the whole- 

 coloured multitude, was a result of migration. But, on 

 the contrary, it is known that the common rat in India 

 is whole coloured and that the white-bellied variety 

 occurs in groups here and there. This was found by 

 Captain Davys, I. M.S., in the Amritzar district, in which 

 over twenty-two thousand rats were captured in sixty-nine 

 villages. Of these villages, sixty-six contained whole- 

 coloured rats only, while three villages contained rats of 

 both kinds. About ten per cent, of those caught in each 

 of the three villages were of the white-bellied kind. The 

 three villages were not situated close to one another. If 

 we consider this case alone there is perhaps small reason to 

 believe that the origin of the three groups was independent 

 in each case, but when considered in conjunction with the 

 case at Poona and with the facts now to be related concern- 

 ing the distribution of white-bellied rats throughout India 

 in general, it seems certain that the various groups, must 

 have arisen independently, on separate occasions, in 

 different places. 



The facts concerning the distribution of the white- 

 bellied rats throughout India were obtained in the 



