The Senses of Animals. 249 



temperature-sense. Goldschneider and others have shown 

 that on the skin of the human hand, for example, there are 

 special points that are sensitive to heat and cold. Some 

 of these little specialized areas are sensitive to cold; 

 others are sensitive to heat ; and neither of these seem to 

 be sensitive to pressure. It therefore seems probable that 

 special nerve-fibrils are set apart for the temperature- 

 sense ; but of the manner in which these fibrils terminate 

 little or nothing is known. 



Let us note that this temperature-sense, unlike the 

 sense of touch, may make us aware of distant bodies. It 

 is, tl^n, what we may term a tekesthetic sense in contra- 

 distinction to a contact-sense. It is stimulated by a 

 molecular throb; the throbbing body may be in contact, 

 but it may be as distant as the sun, in which case the 

 molecular pulsations are brought to us on waves of sether. 

 Whether these waves act directly on the nerve end-organs, 

 or indirectly on them through the warming of the skin- 

 surface in which they terminate, we cannot say for certain. 

 But if the hand be held before a heated stove and be 

 sheltered from the heat by a screen, the removal of the 

 screen, even for the fraction of a second, gives rise to a 

 strong stimulation of the temperature-sense, though the 

 skin-surface be not appreciably raised in temperature. 

 Hence it is probable that the end-organs are stimulated 

 directly, and not indirectly. 



Concerning the temperature-sense in the lower animals, 

 nothing definite is known. But it is impossible to see our 

 familiar pets basking in the sunshine, or a butterfly sunning 

 itself on a bright summer's day, without feeling confident 

 that the temperature-sense is a channel of keen enjoy- 

 ment. As before mentioned, however, this is not to be 

 regarded as the primary end in sensation. The primary 

 end is not life-enjoyment, but life-preservation. And we 

 must regard the temperature-sense as developed in the 

 first instance to enable the organism to escape from the 

 ill effects of deleterious heat or cold, and to seek those 

 temperature -conditions which are most helpful to the 



