no THE GROWTH OF GROUPS 



white-tailed, were found living apart from one another. 

 The principal masses of buildings, the bazaars situated at 

 either end of the lake and certain large buildings close by, 

 contain only the black-tailed kind ; but of eight isolated 

 houses lying at some distance from and above the level 

 of the lake which were investigated, six contained only 

 white-tailed rats, the numbers captured being 4, 5, 7, 3, 3, i. 

 The seventh house contained four white-tailed and two 

 black-tailed rats. In the eighth isolated house one black- 

 tail was captured. These facts are sufficient to show that 

 the two kinds although distinguishable by such a trivial 

 character are segregative, that is to say on the whole 

 they are living apart from one another. 



It is evident that we do not know how this state of 

 affairs came about, for no one observed the vast number 

 of little events which led up to it ; but if we wish to guess 

 at the method, we must be guided by events that we know 

 to have occurred in other places. Hence I arrive at the 

 following conclusion. The progenitors of the white-tailed 

 rats were born from the common black-tailed race. They 

 arose from one or more than one family group, comparable 

 to those found at Rangoon and Poona, the members of 

 which were distinguishable, even at first, from the common 

 race. It was their custom, we know not why, to live 

 apart from the common kind and to breed among them- 

 selves. The chief masses of buildings were strongly 

 occupied by the common kind, consequently they found 

 a place in the outlying buildings. 



The two kinds, the black-tailed and the white-tailed, 

 are quite distinct from one another, no one would hesitate 

 in sorting them. But neither kind can be regarded 

 strictly as a pure race. After examining all the members 



