CHEMICAL COMPOSITION OF THE TISSUES. 79 



boiled. In this respect, blood resembles pure muscular tissue and 

 nervous tissue, and differs from the connective, cartilaginous, and 

 osseous tissues. Blood has, indeed, been called liquid flesh, and it 

 contains nearly as much solid matter as flesh, for the blood contains 

 one-fifth, and muscle one-fourth, of its weight of solids. The analyses 

 of the blood by various chemists, present very different results, partly 

 due to the different methods employed, but also, doubtless, to the vari- 

 able composition of this fluid, under different conditions connected with 

 health, exercise, food, temperament, age and sex. Venous and arte- 

 rial blood likewise differ in certain respects. The following table from 

 Lehrnann shows the composition of 1000 parts of blood, calculated from 

 the analysis of venous blood by Lecanu : 



Corpuscles. Plasma. Total. 



Water, 344, 451.45 795.45 



Hsematin, 8.375 8.375 



Globulin and envelopes, . . 141.11 141.11 



Fat, 1.155 .86 2.015 



Extractive matters, ... 1.3 1.97 3.27 



Salts, 4.06 4.275 8.335 



Fibrin, 2.025 2.025 



Albumen, 39.42 39.42 



500. 500. 1000. 



According to this estimate, blood contains about 80 per cent, of 

 water, and 20 of solid matter, the calculated proportions being about 

 79.5 and 20.5. In round numbers, of the 205 parts of v solids, 156 

 belong to the red and white corpuscles, and consist of 141 parts of 

 globulin (modified albumen), 8J parts of hgematin, the red coloring 

 substance, 1 part of fat, 1J of extractive matters, and 4 parts of salts, 

 chiefly salts of potash. The remaining 49 parts of solids belong to 

 the liquor sanguinis, plasma, or fluid part of the blood, and include 

 rather more than 2 parts of blood-fibrin, which goes with the. cor- 

 puscles in the act of clotting ; the rest of these solids are proper to the 

 serum of the blood, and consist of 39J parts of albumen, 1 of fat, 2 of 

 extractive matters, and 4J of salts, chiefly salts of soda. Salts of lime 

 and magnesia also exist in the blood, and likewise traces of silicon and 

 manganese, and even of lead and copper. The soda, potash, lime, and 

 magnesia, are variously combined, so as to form chlorides, phosphates, 

 sulphates, lactates, and carbonates (at least when the blood is burnt 

 to ashes). The distribution of the mineral substances in the blood is 

 peculiar. Thus, the moist red corpuscles contain ten times as much 

 potassium in 1000 parts as the liquor sanguinis, but only one-third as 

 much sodium ; whilst about six times more phosphoric acid may be 

 obtained from the corpuscles than from the liquor sanguinis, but only 

 about half as much chlorine. The chloride of sodium is, therefore, 

 chiefly contained in the fluid plasma of the blood, and the phosphoric 

 acid principally, and the potassium almost entirely, in the corpuscles, 

 which also contain a large share of the fatty matters. In carnivorous 

 animals, phosphates preponderate in the blood ; in herbivora, carbon- 

 ates abound ; but the chloride of sodium is very constant in both, 

 showing the strong affinity of the animal tissues for that salt. The 

 albumen of the blood is by some believed to be combined with soda, as 



