132 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



one per cent, of sodium phosphate in solution, is able to retain twice the 

 usual amount of carbon dioxide in solution. 



The phosphates of the alkalies are eliminated from the animal body 

 through the kidneys, intestines, and skin. In carnivorous animals, whose 

 blood is rich in phosphates of the alkalies, the urine is the main path of 

 elimination. Through the production of acids, such as uric, hippuric, 

 and sulphuric, the latter originating from the sulphur of albuminoids 

 and their derivatives, a part of the base is withdrawn from the alkaline 

 phosphate, and, as a consequence, the alkaline phosphate now becomes 

 neutral or even acid, thus explaining the production of an acid reaction 

 in urine from the presence of dihydrate sodium phosphate (P0 4 NaH 2 ). 

 Since phosphoric acid, or acid phosphates, in solution give to fluids 

 their power of dissolving calcium and magnesium phosphates, the urine 

 of the carnivora and omnivora is therefore able to hold in solution the 

 earthy phosphates so eliminated. In the case of the herbivora the state 

 of affairs is somewhat different. Here but small amounts of phosphoric 

 salts are found in the urine, although alkaline and earthy phosphates are 

 found in large amount in their food. In this case the phosphates of 

 the food undergo decomposition, and a great part of the base is united 

 with carbonic acid, and so eliminated as alkaline carbonates in the urine, 

 forming thus the characteristic of the urine of herbivorous animals, the 

 earthy carbonates being held in solution by the free carbon dioxide. The 

 phosphoric acid of the phosphates taken in the food of herbivorous 

 animals in greater part unites with calcium and magnesium, and is 

 eliminated through the intestine. Wherever free acid is developed in the 

 tissues of the body acid phosphates are nearly always present and in 

 part contribute to the formation of this acid reaction. This is the more 

 remarkable when it is remembered that these* phosphates have originated 

 from the blood, where they always exist in the form of basic or neutral 

 salts. The explanation of the mode in which this alkaline phosphate is 

 in the different tissues converted into an acid salt is to be explained 

 through the development in the tissues of organic acids, which, as 

 already alluded to in the explanation of elimination of the phosphates, 

 takes a portion of the base from the alkaline phosphate, so developing an 

 acid salt. 



Phosphates appear to be absolutely essential to the development 

 of tissue. This is indicated in the first place by their great abundance 

 in all forming tissues, and even in organizable fluids, and in the fact that 

 the tissues of herbivorous mammals are quite as rich in the phosphates as 

 that of the carnivora, although in the former case they are nearly absent 

 from the blood, and in the latter case are very abundant. In special 

 tissues, such as the muscles, nerves, blood-corpuscles, and ovum, they 

 appear, from their exceptional abundance, to have some special functions 



