VIL] ANIMALS AND PLANTS. 159 



return to their mode of nutrition, and inquire whether 

 certain differences of a more occult character than 

 those imagined to exist by Cuvier, and which certainly 

 hold good for the vast majority of animals and plants, 

 are of universal application. 



A bean may be supplied with water in which salts of 

 ammonia and certain other mineral salts are dissolved 

 in due proportion ; with atmospheric air containing its 

 ordinary minute dose of carbonic acid; and with 

 nothing else but sunlight and heat. Under these 

 circumstances, unnatural as they are, with proper 

 management, the bean will thrust forth its radicle 

 and its plumule ; the former will grow down into 

 roots, the latter grow up into the stem and leaves of 

 a vigorous bean plant ; and this plant will, in due 

 time, flower and produce its crop of beans, just as if it 

 were grown in the garden or in the field. 



The weight of the nitrogenous protein compounds, 

 of the oily, starchy, saccharine and woody substances 

 contained in the full-grown plant and its seeds, will 

 be vastly greater than the weight of the same sub- 

 stances contained in the bean from which it sprang. 

 But nothing has been supplied to the bean save water, 

 carbonic acid, ammonia, potash, lime, iron, and the like, 

 in combination with phosphoric, sulphuric, and other 

 acids. Neither protein, nor fat, nor starch, nor sugar, 

 nor any substance in the slightest degree resembling 

 them, has formed part of the food of the bean. But 

 the weights of the carbon, hydrogen, oxygen, nitrogen, 

 phosphorus, sulphur, and other elementary bodies 

 contained in the bean -plant, and in the seeds which 



