DEFINITIONS AND TECHNICAL CONSIDERATIONS. 339 



of the body are interfered with, and disease may declare itself if continued too 

 long. 



Every part of the body contains water in quantities that appear to vary with 

 the age of the animal. Upon general principles it may be admitted that 50 

 per cent, of the total live weight is water. In newly born animals, this per- 

 centage may reach 80 to 85. 



While in certain cases bones contain 70 per cent, water, when they attain 

 their full development this percentage is only 20. 



The water of the body may be considered as a general solvent; it determines 

 the absorption of the nutritive liquors of the intestines, renders possible a con- 

 tact between various substances and the organs of the body, and in the daily 

 excretions considerable water is found which has helped to carry off the gen- 

 eral wastes of the body. 



Of the mineral substances mention may be made of phosphoric acid and lime, 

 which exist in almost equal proportions, and are about equal to | of the total 

 weight of the ash residuum after incineration of the body; the rest consists 

 mainly of potassa, soda, magnesia, iron, chlorin, sulphuric acid, carbonic 

 acid, and a small percentage of silica. 



Bones are made up mainly of mineral substances. For full-grown animals 

 these represent of their total weight, this percentage varying with the outer, 

 middle and inside parts of the bony frame. About 87 per cent, of the ash 

 from bones is phosphate of lime, the remainder being mainly carbonate of 

 lime. The dried part of bones without fat- contains 27 per cent, phosphoric 

 acid. 38 per cent, lime, and 3 to 4 per cent, carbonic acid. 



Magnesia plays only a very secondary role in the constitution and the main- 

 tenance of animals; its exact functions are almost unknown. Iron is found 

 in quantities representing 0.013 to 0.042 per cent, of the live weight of a full- 

 grown animal in a good condition; its most important functions are in the 

 blood; it is the essential element upon which the coloring of blood depends* 

 its existence is essential to the good health of animals, as shown in the experi- 

 ments of Hosslin. When not in sufficient quantity, the animals were tired 

 and had a very active circulation, owing to the absence of haemoglobin. The 

 arterial blood contains oxyha?moglobin, in which is found 0.45 per cent. iron. 



The blood always contains alkalies and a certain percentage of sodic chlorid, 

 so important for the regular working of the functions of nutrition and respira* 

 tion. They must be constantly renewed so as to assure the proper workings 

 of all organs connected with assimilation. 



The functions of potassa appear to be confined to the formation of tissue 

 cells. The weight of potassa and soda combined that should be fed per diem, 

 is 300 grs. per 100 k. live weight. These alkalies are constantly eliminated 

 through the urine, and the fodders must not be deficient in them. In fact, 

 numerous experiments in feeding without mineral salts soon resulted in death, 

 notwithstanding the fact that the body appeared to be in a perfectly healthy 

 condition. The blood and brain lost 10 percent, of their water under this 

 regimen, and this was followed by a general decrease in phosphoric acid. etc. 

 The fodders for young animals should never be deficient in lime and phos- 



