THE HISTORY AND ZOOLOGICAL POSITION OF THE ALBINO RAT. 



By Henry Herbert Donaldson, Ph.D., Sc.D. 



The common rats in the United States live usually in close association with 

 man. They have been introduced from Europe. There are two species; Mus 

 rattus, with its gray variety Mus rattus alexandrinus , and Mus norvegicus, the 

 Norway rat, our present common form. The fourth form, the albino rat (M us 

 norvegicus albinus), derived from Mus norvegicus, is known only as a domesticated 

 strain. 



Mus norvegicus probably originated in central Asia, where an indigenous form, 

 Mus humiliatus, may represent the parent stock, while Mus rattus seems to be 

 native in Persia and India. 



' Both species have migrated westward across Europe and to the Americas 

 within the last seven or eight hundred years. The migration of Mus rattus pre- 

 ceded that of Mus norvegicus by some six hundred years, but as the Norway rat 

 is the more ferocious and powerful species, it has become dominant wherever it 

 has followed the black rat. 



Nevertheless in many places where the black rat is said to have been extermi- 

 nated, it still survives in small numbers. 



The early history of these migrations is of necessity vague and incomplete and 

 even in the later times when dates are given for the appearance of the Norway rat 

 in various countries, it must be remembered that these might have been present 

 for considerable periods without appearing in numbers sufficient to cause com- 

 ment. 



The Greek and Roman writers before the present era do not seem to have 

 been acquainted with the rat, which therefore, even if present, was probably not 

 abundant at that time on the north shores of the Mediterranean. 



The first reference to the rat in natural history appears about 220 A. D. in 

 Be Natura Animalium by Claudius iElianus. 



In this case we assume that M us rattus is the form meant. Probably as far 

 back as the Volkerwanderung (400-1100 A. D.) and later as the result of opening 

 trade routes with the east during the crusades, the black rat reached Europe. 

 It is reported to have arrived there as early as the twelfth century (Leunis, '83) 

 or the thirteenth century (Thomas, '86), being mentioned by Albertus Magnus— 

 the doctor universalis— {1193-1280) . It was of course probably present for some 

 time before it was noted. 



Thus the European rat of the middle ages, the rat of the legends, of the u Pied 

 Piper" (1284), of the great plagues (before 1700) and of the early anathemas 

 against vermin, was Mus rattus. 



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