CHAPTER 11 



LIFE HISTORY AND DISTINGUISHING CHARACTERS 



NORWAY RAT 



1. Introduction. 2. Life history. 3. Comparison of Norway with Albino. 

 4. Similarities of Norways and Albinos in western Europe and United States. 



1. Introduction. To obtain more complete information con- 

 cerning the rat it is important to note differences which may ap- 

 pear between the domesticated Albino and the wild Norway. 

 Since the wild Norway represents the parent stock it might seem 

 proper to use that form as the standard and to record the devia- 

 tions of the Albino from it. As a matter of fact however our in- 

 formation with regard to the Albino is so much the more complete 

 that the best results will follow from using it as the standard, 

 despite that fact that zoologically it is but a variety of the Norway. 



The wild Norway rat has special value as a form with which 

 the effect of domestication can be systematically studied. 

 It must always be remembered in this connection however that 

 only a limited series of observations can be made on the strictly 

 wild Norway. Many of the observations here to be presented are 

 on the caged and partially domesticated strains, and since this 

 treatment tends to modify several characters in the wild Norway, 

 care will be taken to state clearly just which strain of Norway was 

 used for observation. 



2. Life history. As regards behavior, the Norway rat is very 

 responsive to sounds, gnaws its cage, burrows when opportunity 

 offers, is hard to handle and appears fierce because usually in a 

 state of terror, yet after some days in a cage, mature rats occasion- 

 ally become quite docile. On occasion it swims and dives. 



The Hagedoorns ('17) note that when taken at weaning the 

 Norways (in Java) are readily tamed. The half grown animals 

 resist taming, while the full grown, even if caught wild, tend to 

 be more responsive. They also note the appearance of waltzing 



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