DECAY AND NUTRITION. 243 



CHAPTER XIII. 



OF DECAY AND NUTRITION. 



Of Decay : Loss of Weight in Starvation. Interstitial Death. Effect of Allotropism. 



Of Nutrition : Nutrition for Repair and Nutrition for Remodeling, illustrated in the cases of Fat 

 and Bone respectively. 



Of Fat: Its Peculiarities, modes of Occurrence, and Origin. Inquiry whether Animals ever form 

 Fat. Artificial Production of it. Animals both collect it and make it. Accumulation of it 

 expends Nitrogenized Tissue. Conditions of the Fattening of Animals. Summary of the 

 Sources, Deposit, and manner of Removal of Fat. Its partial Oxidations. Summary of its 

 Uses. Nitrogenized Nutrition. 



Of Bone: The Skeleton. Structure and Chemical Composition of Bone. Sources of its Con- 

 stituents. The Process of Ossification. Experiments on the Growth of Bone. Influence of 

 Physical Agents on Development and Nutrition. 



OF DECAY. 



THE animal mechanism, as a condition of its activity, is constantly 

 giving rise to wasted products, its parts in succession passing Retro rade 

 through retrograde metamorphosis or decay. From the elab- metamorpho- 

 orate organization which they have maintained, they go by 

 degrees through a descending course, which brings them nearer and 

 nearer to the inorganic state. Thus the fats, falling from one step to an- 

 other, finally emerge from the system as -carbonic acid and water, and 

 thus the complex atom of protein degenerates into those substances and 

 ammonia. 



To this steady wasting away we offer no resistance. Having no in* 

 terior principle of conservation, the organism delivers itself LOSS of weight 

 up unresistingly, and, if its necessary supplies be withheld, in starvati n. 

 very soon succumbs. The experiments of Chossat show that, taking the 

 mean of forty-eight cases> including rabbits, Guinea-pigs, turtle-doves, 

 pigeons, hens, and crows, the body loses 39.7 per cent, of its weight be- 

 fore death by starvation ensues ; that mammals, during the process of 

 inanition, lose daily 4.0 per cent, of their weight ; and birds, as indeed 

 might be expected from their higher rate of respiration, 4.4 per cent. It 

 follows, therefore, that such animals, under these circumstances, lose one 

 twenty-fourth part of their weight per diem by destruction of tissue, a 

 result which corresponds with that of Schmidt's experiments, which lead 

 to the inference that the daily amount of properly-selected food which an 

 animal requires must amount at least to one twenty-third of its bodily 

 weight. 



That the functional activity of a part implies destruction is very well 



