Comp. Blood consists of a transparent and nearly colourless fluid (plas′ma, se′′rum, sĕralbu′men), in which float about a countless multitude of microscopic round red bodies (blood-discs, blood-corpuscles), to which its colour is due, accompanied by a few colourless globules (white blood-corpuscles) of a somewhat larger size. The red corpuscles are found, on more minute examination, to consist of an envelope containing a solution of hæmatosin.

Prop. These are, for the most part, well known. It has an alkaline reaction, a saline and rather disagreeable sweetish taste, and when newly drawn evolves a peculiar odour or halitus, which almost immediately disappears. As it cools and on repose it coagulates, owing, according to some, to the spontaneous solidification of the fibrine.

The following table, based upon the observations of Schmidt and the analysis of Lehmann, is given by the latter, as representing the average quantitative relation of the principal constituents of normal blood. It will be noticed that the blood is here regarded as composed of two portions, one consisting solely of the red particles, and the other of the

liquid, in which these red corpuscles are suspended, termed the liquor sanguinis, which consists of the serum holding fibre in solution:—

Sp. gr. of Blood-corpuscles, 1·0885.

1000 parts blood-corpuscles contain—
Water688·00
Solid constituents312·00
consisting of—
Hæmatin (with iron)16·75
Globulin and cell membrane282·22
Fat2·31
Extractive matters2·60
Mineral substances (without iron)8·12
Chlorine1·686
Sulphuric anhydride (SO3)0·066
Phosphoric anhydride (P2O5)1·134
Potassium3·328
Sodium1·052
Oxygen0·667
Calcium phosphate0·114
Magnesium phosphate0·073

Sp. gr. of Liquor Sanguinis, 1·028.

1000 parts of liquor sanguinis contain—
Water902·90
Solid constituents97·10
consisting of—
Fibrin4·05
Albumen78·84
Fat1·72
Extractive matters3·94
Mineral substances8·55
Chlorine3·644
Sulphuric anhydride (SO3)0·115
Phosphoric anhydride (P2O5)0·191
Potassium0·323
Sodium3·341
Oxygen0·403
Calcium phosphate0·311
Magnesium phosphate0·222

The ash of blood contains about 6·84 per cent. of ferric oxide. (Lehmann.)

The following table gives the results of the average composition of human blood in man and woman, according to the analyses of Becquerel and Rodie: