312 ANIMAL REPORT SMITHSONIAN INSTITUTION, 1941 



could induce the evidences of ill healtli that frequently can be recog- 

 nized in captive animals. These experiments obviously showed that 

 some captive animals do not receive all of the food constituents 

 needed by them. In some of his experiments, he supplied the rats 

 with what would normally be considered good varied diets, but he 

 also offered them the test-tube foods so that they could choose from 

 them any ingredient that they might feel they needed. He found 

 that they would frequently take certain test-tube food, thereby dem- 

 onstrating that the supposedly good general diet they were receiving 

 was deficient in certain constituents necessary for their welfare, and 

 realizing this lack, they made it up by taking the relatively unpalata- 

 ble test-tube material. 



An example of deficiency due to an inadequate diet, and what can 

 be accomplished by supplying a suitable diet, is the case of a wood- 

 chuck that was in the National Zoological Park. It became almost 

 completely naked, and remained so over a period of 2 or 3 years. It 

 was fed by Dr. Richter on his chemically complete diet, and at the 

 end of 4 months was returned to the Zoo with as good a coat of fur 

 as a wild marmot would ordinarily have. This animal, together with 

 others of its kind in the National Zoological Park, had been fed with 

 what was supposedly a varied, well-balanced diet, but obviously some- 

 thing was lacking which prevented its growing good fur. This is a 

 clue which should be followed up in the hope that the specific food 

 requirement may be found for the growing of hair. It would benefit 

 many mammals that have a tendency to become naked in captivity, 

 and perhaps some of the birds that suffer from feather loss. Con- 

 ceivably it might even be useful to bald-headed men. 



Grooming is an important activity in the lives of animals, and they 

 will ordinarily take good care of their coats if they feel well. If 

 they fail in this, it may be because of ill health or because they lack 

 proper facilities. Some must have water for bathing; others, fine 

 sand or dust ; others enjoy a shower bath, and still others need to bathe 

 in mud. Large mammals, such as elephants, rhinoceroses, and hogs, 

 delight in daily baths of mud or water, which assist them in avoiding 

 msect pests and parasites. 



If a mammal does not shed its old fur and keep sleek and well- 

 groomed, it is a sign that something is wrong, probably in the diet. 



In addition to correcting the diet, it is well to provide bundles of '■ 

 brush in the cage so that the animal can comb out its fur by rubbing 

 against it, as it would comb its fur in the wild by going through 

 vegetation. 



Human standards of cleanliness should not be the sole factor in 

 determining cage arrangements and accessories. Fresh soil and mud 



