134 ROTATION OF CROPS. 



milk, without restoring this in the food, the lime will be obtained 

 from its bones, which will thus lose gradually their strength and 

 solidity, until they are no longer able to support the weight of the 

 body. But if we give to the pigeon as food barley or peas, and 

 to the cow barley-straw or clover, we will be able to sustain th -, 

 health of the animals ; for these materials abound in salts of 

 lime.* 



Man and animals receive the constituents of their blood and of 

 their bodies from the vegetable world ; and an Infinite Wisdom 

 has so ordained, that the life and luxuriance of plants is strictly 

 connected with the reception of the same mineral substances 

 that are indispensable for the development of the animal organ- 

 ism ; without the presence of the inorganic matters found in the 

 ashes of plants, the formation of the germ, leaves, blossoms, or 

 fruit, could not be effected. 



The amount of nutritive matters in the different kinds of cul- 

 tivated plants is very unequal. The bulbous plants and roots 

 approach each other much more nearly in their chemical consti- 

 tuents than they do the seeds ; while the latter possess always 

 an analogous composition. 



Potatoes, for example, contain from 75 to 77 per cent, of water, 

 and from 23 to 25 per cent, of solid matter. By means of a 

 mechanical process, we may divide the latter into 18 or 19 parts 

 of starch, and 3 or 4 parts of a fibre resembling starch. Both of 

 these added together weigh nearly as much as the dry potatoe. 

 The two per cent, not accounted for consists of salts, and of the. 

 substance containing sulphur and nitrogen, known under the 

 name of albumen. 



Beet contains from 88 to 90 per cent, of water. Five-and- 

 twenty parts of dry beet contain very nearly the same elements 



*The laborers in the mines of South America, whose daily labor (per- 

 haps the most severe in the world) consists in carrying upon their shoul- 

 ders a load of earth of from 180 to 200 lbs. weight, from a depth of 450 

 feet, subsist only upon bread and beans. They would prefer to confine 

 themselves to bread, but their masters have found that they cannot work 

 so much on this diet, and they, therefore, compel them, like horses, to eat 

 beans.- — (Darwin's Journal of Researches.) Beans are proportionally 

 much richer in bone earth than bread. 



