io8 THE GROWTH OF GROUPS 



at the northern and southern ends of the lake ; the out- 

 lying houses are situated upon the sides of the crater, but 

 all the buildings lie within the boundary afforded by the 

 summits of the surrounding hills. The crater lies open 

 to the south, in which direction the lake drains away to 

 the plains in a small stream. The town communicates 

 with the plains by a cart road, which takes much the 

 same direction as the stream. There are a few small 

 hamlets scattered at wide intervals among the surrounding 

 hills, but it is evident that Nainital is more isolated than 

 towns lying on the plains of India. The isolation spoken 

 of here is, of course, in special reference to the rats living 

 within the area. It must be noted that the whole town 

 of Nainital has arisen within the last century. It cannot, 

 of course, be said that during that time no rats have 

 entered the crater from outside, but from the circumstances 

 of the case it is evident that the rodents now living in 

 Nainital are mainly the descendants of those living on 

 the spot before the town began to expand. It is necessary 

 to keep this in mind when considering how these animals 

 came to be as they are. 



Let us now consider their condition at the present day. 

 At Nainital, rats were not being destroyed as a sanitary 

 precaution, consequently the number of animals dealt 

 with is small, being only about fifty. It may be mentioned 

 in passing that it is not an easy matter to obtain rats in 

 large numbers. Any one who wishes to investigate them 

 unaided, must be content to proceed slowly. The chance 

 of a trap, set over night, containing a rat next morning 

 is about one to four ; it varies of course according to the 

 type of trap and the place in which it is set. The large 

 numbers obtained in other places were due to the 



