ON THE ZOOLOGICAL POSITION OF THE ALBINO 



RAT. 1 



SHINKISHI HATAL, PH.D. 

 ASSOCIATE IN NEUROLOGY AT THE WISTAR INSTITUTE. 



According to Leunis ('83) the black rat ( Mns rattits} was known 

 in Europe as early as the twelfth century, while the Encyclo- 

 pedia Britannica (Ol field Thomas, '86) states the appearance of 

 the black rat to be at least as early as the thirteenth century. 

 Although the statements by the different writers as to the ap- 

 pearance of the black rat in Europe do not quite agree, yet it is 

 clear that the arrival of the black rat was much earlier than that 

 of the brown rat (Mi is norvegicusf which, according to various 

 records, appeared in Europe at about the middle of the eighteenth 

 century, or a little earlier. 



Although both species of rats are described as originally 

 natives of Central Asia, yet they are everywhere enemies. By 

 the incessant competition between these two forms, the black 

 rats were almost exterminated, first from Europe, and later from 

 the greater part of North America, and at the end of the eigh- 

 teenth century, the brown rats were alone found in abundance 

 in these regions. 



It is often stated that the white rat at present found in cap- 

 tivity, is the albino of Mits rattits. In support of this view there 

 are a number of statements to be found in the older literature 

 (Donndorff, 1792). (No effort has been made to examine the 

 records previous to Linneus). 



It is apparently on the basis of these records in the older liter- 

 ature that the current statements in popular natural histories and 

 in encyclopedias are based. 



On the other hand, in the zoological literature in the nine- 

 teenth century, there are numerous statements which refer to the 

 albino rats as a variety of Mus dccitinainis. 



1 From the Wistar Institute of Anatomy and Biology at Philadelphia. 



2 Ahts tinn'e^i, us, Krxleben = Mus dc.ntiianiis Pall, of older Zoological Litera- 

 ture. Norvegieus has priority, and has come into general use within the last two or 

 three years. 



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