CHOICE OF FOOD FOR THE IJHKKPINU-MARE. 539 



proximate principles, otherwise called proteine compounds 

 namely, fibrine, albumen, caseine, or legumine. These proxi- 

 mate principles may be regarded as common to all kinds of 

 food rightly described as perfectly nourishing, or as flesh- 

 formers. But as the framework of the body even of the foal 

 requires not pnly carbon, hydrogen, oxygen, and nitrogen, but 

 also such simple substances as chlorine, fluorine, sulphur, 

 phosphorus, silicon, potassium, sodium, calcium, magnesium, 

 iron it is necessary to ascertain that these last-named mineral 

 substances are sufficiently supplied in the food of the mare to 

 enable her system to impart them to the embryo foal with that 

 freedom which perfect development requires. 



The pregnancy of the mare lasts for eleven months, and 

 during all this period there is a drain on the mother to supply 

 the materials necessary for the development of the frame of 

 the foal. In the early stage of her pregnancy, the drain is of 

 course very small, but it grows greater and greater as the 

 pregnancy advances. How mysterious soever may be the 

 connection between the blood of the mother and the blood of 

 the foetus in the placenta, it is certain that the development 

 of the bodily frame of the foal takes place exclusively at the 

 expense of the blood of the mother. Thus there is no room 

 for doubt that the blood of the mother during pregnancy, 

 when proper food is supplied, undergoes changes of a kind 

 to fit it to afford, at each succeeding stage, such materials as 

 the exigencies of development in the foetus at that stage re- 

 quire. The only well-marked change that has been observed 

 on the blood in mammals during pregnancy is an increase in 

 the proportion of fibrine. This has long been known, as re- 

 spects the human race, by the fact that blood drawn from a 

 vein during pregnancy uniformly shows the same buffy coat, 

 composed of fibrine, which is present in blood drawn during 

 acute inflammation. The presence of fibrine in larger proper- 



