THE GROWING ANIMAL AND THE MIliK COW. 617 



milk cow, which has little muscle or fat to waste away, and, therefore, 

 little to repair, the sustaining food is reduced to the smallest possible 

 quantity. This small portion of food is all that is returned to the hus- 

 bandman in her dung. The phosphates, salts and gluten, and even the 

 starch, of the remainder of the food she eats, are transformed in her 

 system, and appear again in the form of milk. The dung of the milk 

 cow must be very much poorer, and less valuable, compared with the 

 food she eats, than that of any other kind of stock. 



It is true that the bulk of her dung may not be v«ry much less than 

 that of a full-grown animal which is yielding no milk, but this bulk is 

 made up chiefly of the indigestible woody fibre and other comparatively 

 useless substances which her bulky food contains. The ingredients of 

 the milk have been separated from these other substances as the food 

 passed through her body, and hence, though bulky, the dung of the milk 

 cow is colder and less to be esteemed than that of the dry cow or of the 

 full-grown ox. 



Nothing can more strikingly illustrate the difference between the effect 

 of the digestive organs of the fattening ox and those of the milk cow 

 upon the food they consume, than the well-known and remarkable dif- 

 ference in quality which exists between distillery dung, obtained from 

 fattening cattle fed upon the refuse of the distilleries, and cow-feeders' 

 dung, voided by milk cows fed upon nearly the same kind of food — 

 namely, the refuse of the breweries. 



§ 17. Summary of the views illustrated in the present Lecture. 



The topics discussed in this Lecture are of so interesting a kind, and so 

 beautifully connected together, that you will permit me, I am sure, 

 briefly to draw your attention again to the most important and leading 

 points. 



1°. It appears that all vegetables contain ready formed — that is, 

 form during their growth from the food on which they live — those sub- 

 stances of which the parts of animals are composed. 



2°. That from the vegetable food it eats, the animal draws directly 

 and ready-formed the materials of its own body — phosphates to form the 

 bones — gluten, &c., to build up its muscles — and oil to lay on in the 

 form of fat. 



3°. That during the process of respiration a full grown man throws 

 off* from his lungs about 8 oz. — a cow or horse five times as much — of 

 carbon every 24 hours ; and that the main office of the starch, gum, and 

 sugar of vegetable food is to supply this carbon. In carnivorous animals 

 it is supplied by the fat of their food — in starving animals, by the fat of 

 their own bodies — and in young animals, which live upon milk, by the 

 milk sugar it contains. 



4°. That muscles, bone, skin, and hair undergo a certain necessary 

 daily waste of substance — a portion of each being removed every day 

 and carried out of the body in the excretions. The main function of the 

 gluten, the phosphates, and the saline substances in the food of the full 

 grown animal, is to replace the portions of the body which are thus re- 

 moved, and to sustain its original condition. Exercise increases this na- 

 tural waste and accelerates the breathing also, so as to render necessary 



