ZOOLOGICAL POSITION OF THE ALBINO RAT. 



O 



69 



As the colonies stand, the albinos are not a strictly homogeneous or homo- 

 zygous population from the standpoint of color, or from the standpoint of many 

 other characters. The differences are, however, not sharply marked, and some- 

 times do not reveal themselves except under very special conditions. Never- 

 theless, the albino rats do not represent a pure strain in the present sense of that 

 term. Indeed it is not possible to obtain a pure strain in any mammal, as it 

 can only follow from reproduction by budding or in forms capable of lf-fertili- 

 zation. 



This completes the survey of rather an interesting case of the distribution of 

 a small mammal and its modifications in captivity. In closing I wish to ( lnpha- 

 size by repetition the points on which information is specially desired. These 

 are as follows: 



1. Colonial records of the appearance of the Norway rat on the eastern 

 seaboard of North America. These are most likely to be found from 1 750 to 1 775. 



2. The earliest date at which the albino rat was observed in the United Statee 



3. The discovery of a living specimen of an albino of Mus rattu>. 



4. News of some conveniently placed island with a continuous food supply 

 where the albinos might be turned loose in order to watch the effects on them 



of a really wild life — especially the effect on the growth of the nervous system 



24 JOURN. ACAD. NAT. SCI. PHILA. VOL. XV. 



