330 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1941 



sprinkled occasionally or dipped in water. Some of the little desert 

 mammals apparently do not know how to drink water from a con- 

 tainer, as they are accustomed to obtaining only occasional drops 

 of dew or rainfall from leaves and stems. Their food may be 

 sprinkled with a little water so that they can get a few drops at a 

 time. Animals that inhabit arid regions usually obtain most of the 

 moisture for their systems either by manufacturing it from dry seeds 

 they eat, or from the vegetation. In captivity, they will obtain much 

 of their required moisture from fresh vegetation, but they should 

 also from time to time be offered a wisp of cotton saturated with 

 water. They may be supplied with water from a little glass sipping 

 tube somewhat like a medicine dropper, with the point bent in U shape 

 so that it operates as a fountain, but will give out the water only a 

 drop at a time as the animal takes it. 



It is entirely possible that the general lack of success in keeping 

 various marine animals in captivity has been due to the failure of the 

 captor to supply them with salt water of suitable composition. Some 

 are accustomed to living alternately in salt and fresh water a part of 

 each year ; others spend their entire lives in either. Some appear to 

 require salt water either for drinking or for its healing and curative 

 properties. However, many marine animals appear to adapt them- 

 selves gradually to fresh water. 



Very satisfactory artificial sea water can be made by dissolving 31^ 

 pounds of Turks Island salt in 100 pounds of fresh water. 



Minerals essential for building body tissues will ordinarily be 

 obtained from the food if the diet is sufficiently varied and the animals' 

 glands are functioning properly. It is, however, often desirable to 

 supply calcium in the form of calcium phosphate, ground bone, or 

 old dried bones on which the animals may chew. 



Enough iodine can usually be supplied in iodized or rock salt if 

 the animal will take it. If not, iodine can be given in organic form, 

 or with the feed. 



Salt requirements seem to vary widely. Salt appears to be essen- 

 tial to the welfare of cattle, sheep, deer, goats, horses, and rabbits, 

 but is rejected by many animals. A safe plan is to offer it to almost 

 all, and let them accept or refuse. 



Many prepared foods can be used advantageously, such as some of 

 the canned meats and meat mixtures. In addition, zoos and animal 

 keepers have developed certain other foods which are listed below, 

 together with formulas for two of them. 



Bear bread. — The National Zoological Park uses bread made up in quantities 

 of about 200 pounds at a time as follows : 100 pounds of flour, 60 pounds of bran, 

 2 pounds of salt, Va pound of yeast, and 1 pound of blackstrap molasses. This 

 is thoroughly mixed with water, allowed to rise, and is baked like other breads. 



