ANIMAL CHEMISTRY. 409 



These offices we will indicate so fur as they are ascer- 

 tained. The blood, examined by the microscope, is seen 

 to consist of two parts, an almost colorless liquid called 

 liquor sanguinis, or liquor of the blood, and floating in this 

 are multitudes of rounded particles called globules of the 

 blood, or blood-disks. These are little sacs or vesicles con- 

 taining a fluid, and the iron forms one of the constituents 

 of certain crystalline principles suspended in this fluid. 

 These globules convey the oxygen received in the lungs 

 to all parts of the body, and the liquor sanguinis probably 

 brings back to the lungs the carbonic acid which is to be 

 discharged there. The crystalline bodies containing iron 

 act as common carriers for oxygen. When iron is deficient 

 in the blood some form of iron medicine is administered by 

 the physician. 



580. Salt. The amount of salt in the blood is about 

 three times that of iron. Though it is nowhere present as 

 a part of any tissue, it is of much service in the formative 

 processes, both as salt and by its elements, it being to some 

 extent decomposed in the body. There is no salt found in 

 the juices of muscles, but one of its elements, chlorine, is 

 found there combined with potassium, and this element is 

 undoubtedly derived from the salt in the blood. In the 

 bile of land animals there is soda, derived from the same 

 source. Then there is hydrochloric acid, an efficient part 

 of the gastric juice in the process of digestion, which is 

 furnished in some way from the decomposition of salt. We 

 use salt instinctively with our food with some articles, as 

 potatoes, more than with others. As it is not as abundant 

 in plants as it is in animal food, considerable pains are taken 

 to supply our domestic herbivorous animals with a suf- 

 ficiency of this important article of diet. And, to meet the 

 instinctive desire of the wild animals for it, there are places 

 where it exists in the soil, to which they can resort for it. 



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