34 GENERAL RELATIONS BETWEEN THE SOIL, 



or first stomach, and chew it over again before they allow it to 

 pass down to the lower stomachs. Animals with simple stomachs 

 never ruminate. The intestines of these animals also differ in 

 length from those of the ruminants. Thus, while those of the 

 horse are ten times, and those of the pig sixteen, the intestines 

 of the cow are twenty-two, and those of the sheep twenty-seven 

 times the length of the body. 



It must be obvious to the most superficial, therefore 

 1. That the same kinds of food, whatever be their chemical 

 composition, are not equally adapted to the stomachs of all 

 animals. And 



2. That the form in which the food is given, is nearly as 

 important to an animal as its composition ; and that, to produce 

 the maximum effect upon each animal, this form should have a 

 special adaptation to the peculiar structure of the digestive 

 organs of that animal. 



8. General relations between the soil, the plant, and the animal. 



And when possessed of the several kinds of knowledge to 

 which I have adverted in the preceding sections, the experi- 

 menter will find his task made more easy by the light which 

 each of these branches throws upon the other. He will see 

 that there is a natural and close relation between the soil, the 

 plant, and the animal, which is not only simple and beneficial, 

 but which is pregnant with useful practical instruction. 



If nitrogen exists in, is necessary to, and by natural opera- 

 tions becomes fixed in the soil, it is because the plant cannot 

 form its gluten and albumen without it. If the plant form 

 gluten, it is that it may, as its last service, convey into the 

 stomach the raw material, out of which the muscles of the animal 

 are to be directly built up, and without unnecessary labour to 

 the digestive organs. If food containing much of the gluten is 

 remarkably nourishing, it is because on the full maintaining of 

 the muscles the sustenance and strength of the animal chiefly 

 depends. And if the urine promote vegetation in a high degree, 

 it is because the nitrogen of the decomposed muscle is in large 

 proportion contained in it. 



Again, if the soil contain always common salt, which passes 



