80 ANATOMY. 



a so-called alburqinate. The blood has a saline taste, and is an alka- 

 line fluid, its alkalinity depending either on a carbonate or an alkaline 

 phosphate of soda. The crystallizable extractive matters of blood 

 consist chiefly of creatin and creatinin, but also include hypoxanthin 

 or sarcin, leucin, tyrosin (in disease), hippuric acid, and even urea and 

 uric acid in minute quantities. There are also, in certain kinds of 

 blood, traces of grape sugar, or of the amyloid substance, glycogen, as 

 in the blood of the hepatic veins, vena cava inferior, right auricle, and 

 pulmonary artery. All blood contains traces of coloring substances 

 like those of the bile, and odoriferous substances like those of the flesh. 

 The odor of blood differs in different animals ; in man it is said to be 

 sometimes garlicky : it is supposed to be due to a fatty acid, and may 

 be rendered more distinct by the addition of sulphuric acid, even to 

 old specimens of dried blood. Lastly, the blood contains carbonic 

 acid, oxygen, and nitrogen gases, in various proportions in different 

 kinds of blood, and held in solution, or in some feeble state of combi- 

 nation, as will be more fully explained in the chapter on Respiration. 

 The fluid plasma, which pervades all the tissues, must also hold in 

 solution nearly all the constituents of the blood, including the gases 

 just enumerated. Whilst" the solid and liquid constituents of the 

 blood are its nutrient part, the oxygen dissolved, or otherwise loosely 

 combined in it, is its most energetic, chemical, and stimulating ingre- 

 dient. The special uses of its several constituents will be considered 

 in the chapter on the Circulation. 



The chyle and lymph have a similar composition to blood, but they 

 are both much more watery, and contain far less solid matter, the 

 chyle being the richer of the two, that is to say, during digestion ; but 

 during fasting it has the same composition as the lymph. Chyle taken 

 from a donkey has been found to contain about 900 parts, and human 

 lymph about 970 parts, of water, in 1000. The 100 parts of solids in 

 the chyle were found to consist of 36 of albumen, 4 of fibrin, 36 of 

 fat, 15 of extractive matters, and 9 of salts. The 30 parts of solids 

 in the lymph, consisted of 4J parts of albumen, 5 parts of fibrin, 2J 

 of fat, 3 of extractive matters, and 15 of salts. Other analyses give 

 different results ; but the chyle, speaking generally, is distinguished 

 from lymph, by containing more albumen, and much more fat; hence, 

 after coagulation, the serum of chyle is more fatty than that of lymph. 

 In comparison with blood, chyle contains much less albumen, but 

 much more fat, and usually no coloring matter. The lymph of the 

 lymphatics contains traces of sugar and urea; in the lymphatic glands 

 leucin has been detected. The salts of the blood, chyle, and lymph, 

 are very similar, only those of the blood are richer in phosphates. 

 The lymph, like the blood, has a saline taste, and is alkaline; but 

 the chyle is sometimes neutral, or only slightly alkaline. 



The serous and synovial epithelia differ probably but little from 

 albuminous substances; but the mucous epithelia, consisting of mucin, 

 have more decided characters, approaching those of horn. The epi- 

 dermis, and its appendages, the nails and hairs, consist chiefly of 

 keratin with a little fat. Their ashes contain lime and iron, and 

 those of the hair, traces even of silicon and of the metal manganese. 



