ANIMAL BEHAVIOR — WALKER 303 



outward until the full length of the tail has passed through the 

 lips and hands. The whiskers are very important organs of touch. 

 Therefore, they are often straightened and adjusted. The skins 

 of desert animals secrete considerable oil for their fur. This is 

 shown by the fact that the hairs stick together and the coat becomes 

 very unsightly if the little creatures do not have access to sand 

 for a day or two. 



Many people wlio have seen little furry creatures scratching them- 

 selves have assumed that this action indicates infestation by fleas 

 or other parasites. However, most animals are very clean and have 

 relatively few external parasites. Some have apparently learned 

 that tobacco is an excellent insecticide. I recently discovered that 

 my pet grasshopper mouse would chew up bits of tobacco, then open 

 his fur with his hands and place the chewed tobacco in his fur close to 

 his skin. This was plainly the application of tobacco to spots that 

 were itchy. In this particular case the animal had been so well 

 supplied with insect powder that he had no external parasites. He 

 apparently did not distinguish between the normal itchiness to 

 which little furry creatures are subject and the external parasites 

 that would be killed by tobacco. 



Semiaquatic animals like the beaver wear coats that are com- 

 posed of two important layers — the long coarse guard hairs (that 

 give the coat its rough appearance) and the very dense coat of fine 

 silky short under hair which insulates the animal and is, if well 

 cared for, impervious to water. Proper care of the coat is of great 

 importance to the beaver. Almost immediately after coming out 

 of the water, he will begin a painstaking grooming by which he will 

 wipe or rub off most of the surplus water. Then he will proceed to 

 comb out the fur until it is dry and loose. It has been found that if 

 beavers and some other animals cannot groom their fur and dry it 

 out they become very susceptible to pneumonia and related ailments. 



It is a common sight to see monkeys carefully grooming each 

 other's fur. Most visitors to the Zoo mistakenly believe that this 

 activity is a search for parasites. But, as a matter of fact, parasites 

 are so extremely rare on monkeys that their presence can in no way 

 accomit for the grooming habit. Grooming is apparently an enjoy- 

 able process of cleaning the fur and skin. It probably finds its 

 exact counterpart among human beings in the pleasure most people 

 take in having their backs scratched and in the soothing, almost hyp- 

 notic effect of the treatment received in beauty parlors and barber 

 shops.® 



"Grooming by animals is more than a mere drpssing of the coat. It has a definite part 

 in the social lives of the animals. Ccnsiderable has been written on this subject, one paper 

 being "Sham louse-picking, or groolning among monkeys." by H. E. Ewing, Journ. Mamm., 

 vol. 16. pp. 3DS-306, November 1835. 



