INORGANIC SUBSTANCES. 157 
is a clear yellowish liquid of alkaline reaction and sp. gr. about 1027-1031. 
It contains about 90 per cent, of water, holding various organic and 
inorganic substances in solution. With the exception of certain proteids, 
the constituents of plasma are identical with those of serum, in which 
bhey are more readily studied. 
Inorganic substances. — Plasma consists to about 90 per cent, of 
water. The inorganic salts occur to the amount of about - 8 per cent. 
The principal is chloride of Bodium. This can be crystallised out from 
plasma after inspissation. According to the analyses of C. Schmidt, it 
is present to the extent of - 55 per cent. Carbonate of soda is probably 
the next most abundant salt, although its exact amount cannot be stated. 
It is to this salt that plasma mainly owes its alkalinity and its power of 
absorbing carbonic acid. Although it is not possible to state definitely 
in what manner the acids and bases of the plasma are distributed, it 
appears probable that, besides these two salts, chloride of potassium, 
sulphate of potassium, phosphate of calcium, phosphate of sodium, and 
phosphate of magnesium, and probably chloride of calcium, occur l in 
small amounts. Traces of a fluoride have also been found. 2 
Gases. — The gases of plasma have not been satisfactorily investi- 
gated. They are probably not very different from those of serum, 
which in the dog consist of from 43 to 57 vols, of carbonic anhydride, 
2 - 25 of nitrogen, and - 25 of oxygen. 3 The oxygen and nitrogen are 
probably simply dissolved in the plasma, but the carbonic anhydride 
is present in far too great an amount for this to be the case, since 
not more than 2 or 3 vols, per cent, of this gas could be dissolved. The 
remaining amount must therefore be in chemical combination. This can 
only be with soda, as carbonate and bicarbonate; for other bases are 
present in too small amount in plasma to be taken into serious considera- 
tion. This statement is also true for alkaline phosphates, although in 
the corpuscles, in which they are present in considerable quantity, they 
may play an important part in fixing CO;, (Bunge), as shown by the 
foil 1 wing equation : — 
Na 2 HP0 4 + H3CO3 = H 2 P0 4 + NaHC0 3 . 
Some of the C0 2 may be combined with proteid, 4 but this can only be 
very little. As a matter of fact, Bunge calculates that, after allowing 
for the amoimt of soda required to saturate the only strong mineral acid 
of the plasma (hydrochloric), there is enough left to fix 63 vols, per cent, 
of CO, as carbonate, and an equal additional amoimt as bicarbonate, 
which is far more than the amount of C0 2 actually present."' 
Organic constituents of blood plasma. — The organic constituents 
of plasma may be divided into proteids and non-proteids, and the latter 
into nitrogenous and non-nitrogenous. 
Non-nitrogenous organic substances found in plasma. — These 
consist of carbohydrates and fats; and, in addition, there are present 
small quantities of a lipochrome, of cholesterin, and probably of sarco- 
lactic acid. 
Carbohydrates of plasma. — Three carbohydrates have been described 
1 Pribram, Abhandl. d. math.-phys. CI. d. k. Sachs. Gcsdlsch. d. IFissensch., Math.-phys. 
Klasse, 1871, Bd. xxiii. S. 279 ; and in Arb. a. d. physiol. Anst. zu Leipzig, 1871, p. 63. 
2 Tammann, Ztschr. f. physiol. Chem., Strassburg, 1888, Bd. xii. S. 325. 
3 Bunge, op. cit., S. 286. 
4 Sertoli, Hoppe-Seylers Med. Chem. Untersuch., Berlin, 1868, Heft 3, S. 350. 
5 Op. cit., S. 286. 
