244 PHILOSOPHY OF ZOOLOGY. 



stance, with this modification, that soft substances are 

 ferred in youth. In the mammalia, the appetite is directed 

 to liquids alone, the milk of the mother, in the first periods 

 of existence, and, afterwards, to a mixture of solids and 

 fluids. Yet this instinctive power regulates with equal 

 success, in these different periods, the disimilar movements 

 of sucking and chewing. 



In many animals, such as the mammalia, the nourish- 

 ment of the first period of life is provided by the parents, so 

 that all the exertion necessary for this instinctive power to 

 make, is confined to the proper employment of the food thus 

 brought within the reach of the suitable organs. But, 

 with many other animals, the case is widely different. They 

 are brought forth in situations where there is no parent to 

 assist this appetite, nor food provided for its supply. In 

 such cases, this instinct must execute more complicated 

 movements, and lead the individual to those places where 

 food is to be obtained, and afterwards direct the choice. It 

 is this influence that guides the caterpillar to the leaf, the 

 duckling to the pool, and the samlet to the ocean. 



Under the controul of this appetite, and, prior to all ex- 

 perience, each species is directed to seek the kind of food 

 which affords it the most suitable nourishment, and to shun 

 that which would be deleterious. Thus, in looking at a pas- 

 tured field, we observe that there are some plants which are 

 left untouched, while others are cropped to the ground. But 

 as the tastes of animals, in this respect, are exceedingly 

 various, we observe that what is left untouched by one spe- 

 cies, is greedily devoured by another. Nay, what is eaten 

 by the goat, for example, with avidity, and with impunity 

 by the horse or sheep, as the water-hemlock (Cicuta virosa,) 

 is certain poison to the cow. Hence it has been called wo,, 

 ter cowlane, and we have heard a Fiff shire fanner, with a 



