CARE OF CAPTIVE ANIMALS — WALKER 311 



these conditions must be produced at a minimum of cost. The many 

 fur farms in the northern United States, in Canada and Alaska, as 

 well as elsewhere in the world, carry on a variety of research work 

 looking toward more successful fur farming. Veterinarians have 

 been employed who are not merely animal doctors and surgeons, but 

 who carry on active research in well-equipped laboratories and make 

 many painstaking and accurate observations. Experimental fur 

 farms of governmental agencies, such as that operated by the former 

 Biological Survey and now carried on by the Fish and Wildlife 

 Service at Saratoga Springs, N. Y. ; their rabbit experiment station 

 at Fontana, Calif., the Canadian fox experimental station at Sum- 

 merside. Prince Edward Island, and others are at work on these 

 problems. As a result of these studies by individuals, companies, and 

 governmental agencies, a wonderful fund of information about the 

 care of fur-bearing animals has been developed. Some of this is avail- 

 able in Government or other publications that are cited in the bibliogra- 

 phy at the end of this paper. Naturally most of the information 

 developed relates to the raising of foxes, minks, muskrats, rabbits, 

 chinchillas, coypus, and a few other animals, as these are the 

 fur bearers that are commonly raised. However, the researches and 

 experiments have so clearly demonstrated the need of many animals 

 for vitamins, certain foods, and certain types of treatment and care, 

 that the basic principles can well be applied to a much wider variety 

 of animals and to man. Research laboratories that have carried on 

 experimental work with mice, rats, rabbits, guinea pigs, monkeys, and 

 other animals for the purpose of developing information relative to 

 medicines, vaccines, serums, foods and food deficiencies, and for other 

 purposes, have likewise made outstanding contributions. These were, 

 of course, mainly designed to advance the cause of human medicine, 

 but their findings should be freely used by persons interested in 

 keeping animals in captivity in the best possible condition. 



Various studies have been made to determine the chemical constitu- 

 ents necessary for proper diet for animals. These have been carried 

 on in various ways and much valuable information has been devel- 

 oped. Among the studies is the work of Dr. C. P. Richter, of the 

 Psychobiological Laboratory, Johns Hopkins Hospital, who over 

 a long period of years has carried on studies, principally with rats, 

 in which he has clearly demonstrated the importance of furnishing 

 animals with the proper amount of the various food constituents 

 needed by them. He has carried on long feeding experiments with 

 a great number of rats fed on diets composed entirely of solutions 

 of starch, proteins, salts, and other ingredients. On these the ani- 

 mals thrived, remained active and in good health, and developed 

 good coats. He found that by removing certain of these foods, he 



