286 PHYSIOLOGY AT THE FARM. 



termed relative functions namely, those of sensibility and 

 locomotion. The latter, or the relative functions, being almost 

 exclusively the property of animals, are therefore often termed 

 the " animal functions/' 



With respect to the chemical constitution of organic nature, 

 it is to be remarked that there is no simple substance in the 

 vegetable kingdom which is not to be found in the mineral 

 kingdom, and that in the animal kingdom there is no simple 

 substance which does not exist in the vegetable kingdom. It 

 is a nearly absolute rule that the members of the animal 

 kingdom obtain all the materials of their structure, not from 

 the mineral kingdom, but from the vegetable kingdom. And 

 there is this grand difference between these two kingdoms of 

 organic nature that the vegetable kingdom draws its food, 

 in the mineral state, solely from the mineral kingdom, while 

 the animal kingdom feeds on mineral matter hardly at all, but, 

 with the very slightest exceptions, on substances which have 

 been first converted by the vegetable kingdom into organic 

 matter. In short, the food of the vegetable kingdom is 

 mineral the food of the animal kingdom is organic. To this 

 rule, absolute as it seems and really is, a slight qualification 

 may be sought to satisfy some minds. Thus water, which is 

 so imperatively required at all times by the members of the 

 animal kingdom, is taken into that kingdom in the purely 

 mineral state. It is hardly a sufficient answer to say that 

 water is not an aliment, but a drink ; the better mode of 

 removing the objection is to insist that water is not an ali- 

 ment in the same sense as the ordinary organic aliments for 

 it is not decomposed or chemically altered within the living 

 system, but is uniformly diffused as the medium in which the 

 animal organism is sustained. A like objection might be 

 raised in respect to common salt, which is essential to the 

 health of many animals, and is by man uniformly taken in 



