PROTEIDS OF /'LAS.)/. /. 167 
ammonium sulphate, and also in iodides and fluorides, and in solutions 
of urea. 1 It is also very Blowly dissolved to some extent by normal salt 
solution; the solution is in all cases assisted by moderate warmth. Fibrin 
obtained from venous blood is Blightly more soluble in sail solutions than 
that yielded by arterial blood. The proteid material which is found dis- 
solved after solution of fibrin in the above salts is composed of two 
globulins,- having heat coagulation temperatures of 55 c and 75° respec- 
tively. The latter, according to Halliburton, is reduced to 60°-0~> in 
sodium chloride solutions, being 73 -75 £ inmagnesium sulphate solutions 
only. Albumoses are also present in the fluid (limbourg, 1 lastre). This 
solution of fibrin in neutral salts occurs in the entire absence of putre- 
factive decomposition (Green, 1 >astre). Fibrin swells in dilute acid (such 
as - 2 per cent, HC1) into a clear jelly, which very slowly undergoes 
solutii hi with the formation of acid albumin and proteoses. Stronger acids 
and, with the aid of heat, weak acids, effect the conversion more readily. 
The addition of pepsin to the acids employed greatly accelerates the con- 
version, the fibrin first splitting into two glohulins, one coagulating at 56° 
and the other at 75°, and then becoming transformed into acid-albumin, pro- 
teoses, ami peptones. 3 Trypsin in alkaline solutions has a similar action. 4 
Blood yields from "2 to '4- per cent, of its weight of dry fibrin. Ham- 
marsten 5 gives the following as the elementary composition of fibrin : — 
c 
52-68 
S 
1-10 
H 
6-83 

22-48 
N 
16-91 
It is, however, never free from ash, and the ash invariably contains 
lime, 6 but not more than other proteids, 7 nor does it contain more 
lime than the fibrinogen from which it is formed. Thus in one 
experiment Hammarsten found that a sample of fibrin, obtained by 
the action of ferment prepared from oxalated serum, upon fibrinogen 
prepared by precipitation from oxalated plasma by acetic acid, yielded 
exactly the same amount of lime as a sample of the fibrinogen itself, 
namely, 0-055 per cent. This fact completely disposes of the theories of 
coagulation which assume that fibrin is merely a combination of 
fibrinogen with lime, such as those of Freund, Arthus, Pekelharing. and 
Lilienfeld. Fibrin obtained by whipping blood leaves a considerable 
phosphorus-containing residue (nuclein) after subjection to peptic 
digestion : this is probably largely derived from the nucleo-proteids of the 
entangled leucocytes. But even fibrin obtained from solution of purified 
fibrinogen in dilute salt solution yields a certain amoimt of such residue. 8 
It is possible that this may be an accidental impurity, but, on the other 
hand, it may be an integral constituent of the fibrin. 
1 Dastre, Arch, de physiol. norm, ct path., Paris, 1895, p. 408 ; Compt. rend. Acad. d. 
sc, Paris, 1895, tome cxx. p. 589. See also on the solubility of fibrin in neutral salts, 
Holzmann, Arch. f. Physiol., Leipzig, 1884, S. 210; and Arthus, "Coag. des liquides 
organiques," Paris, 1894, pp. 105 et seq. 
'-' Green, Jou.ru. Physiol., Cambridge and London, 1887, vol. viii. p. 372. 
' J Hasebrock, Ztschr.f. physiol. Chem,., Strassburg, Bd. xi. S. 348. 
4 A. Herrmann, ibid., Bd. xi. S. 508. The other literature on this subject will be 
found in Halliburton. "Text-Book of Physiol, and Path. Chemistry." 
5 Arch. f. d. ges. Physiol., Bonn, Bd. xxii. S. 484. 
6 Frederikse, Ztschr. f. physiol. Chem., Strassbirrg, 1894, Bd. xix. S. 143. 
7 Hammarsten, ibid., Bd. xxii. S. 392. 
8 Schafer, Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. 
xvii. p. xx. 
