66 ON MANURE. 



CHAPTER XII. 



On Manure. 



In order to obtain clear ideas on the value and action of ani- 

 mal excrements, it is most important to bear in mind their origin. 

 It is wcH known, that when a man or an animal is deprived of food, 

 he becomes emaciated, and his body diminishes in weight from 

 day to day. This emaciation becomes visible after a few days y 

 and in the case of persons who are starved to death, their fat and 

 muscular substance disappear, their body becomes empty of 

 blood, and at last nothing remains except skin and bones. 



On the other hand, the weight of the body does not alter, even 

 though supplied with sufficient food ; for in the body of a healthy 

 man there is neither a marked increase nor diminution of weight 

 from one twenty-four hours to another. 



These phenomena prove with certainty that a change proceeds 

 in the rganism of an animal during every moment of its life ; 

 and a part of the living substance of the body passes out from it 

 in a state more or less changed. The weight of the body, there- 

 fore, would decrease continually, if the parts separated or changed 

 were not again prepared and replaced. 



The restoration and replacement of the original weight is 

 effected by means of food. 



A man or an animal consumes daily a certain number of oun- 

 ces, or of pounds of bread, flesh, or other nutritive substances, 

 so that in a year he consumes an amount of food of a much 

 greater weight than that of his own body. He takes in the food 

 a certain quantity of carbon, hydrogen, oxygen, nitrogen, and 

 sulphur, as well as a very considerable quantity of mineral in- 

 gredients, which we have learned to know as the ashes of food. 



What, it may be asked, has become of all these constituents 

 of the food, to what purposes have they been applied, and in 



