48 MAMMALS 



quarrelsome in general, and bucks of about the same age 

 may be run together in safety. 



The housing may be the same in principle as for mice. 

 The cage should be larger, of course, say 12" x 12" x 18", as 

 a minimum for a pair of rats. The mesh of the wire may be 

 larger, either one-quarter or one-half inch. Sawdust is the 

 best floor covering, and hay or straw, with a few bits 

 of cloth or paper, the best bedding for the nest box. 



Unless regularly handled and kept very tame, rats are 

 rather more inclined than mice to bite. For this reason, 

 unless known to be perfectly gentle, rats should be handled 

 by the tail only. 



Rats are somewhat coarser feeders than mice, but equal 

 care is required as to their diet. Table scraps or greasy 

 food should never, under any circumstances, be given. Oats 

 should be the standard grain, with occasionally a little wheat 

 and canary. Flax and hemp are useful during cold weather, 

 or as an aid to animals low in condition. Green food and 

 vegetables are a necessity. Mothers and youngsters should 

 have bread and milk, at least during the critical periods. 

 An occasional small, soft bone, free from grease, will fur- 

 nish young rats amusement and much-needed bone-building 

 material. Fresh water should always be at hand. 



Whites, of course, far outnumber all other varieties. 

 They undoubtedly are the oldest form, and are well known 

 where others are unheard of. Young specimens usually 

 are pure white, but as they grow older the coat is likely 

 to take on a yellowish tinge, particularly in bucks. Some- 

 what darkened cages might be of service in avoiding this 

 condition. 



Black rats are not so well known as whites. Just how 

 they originated is not known, but they are now well estab- 

 lished. The color is not dense, as in mice, but usually is 

 of a brownish cast. Also, the feet are almost invariably 



