PROTEIDS OF PLASMA. 167 



ammonium sulphate, and also in iodides and fluorides, and in solutions 

 of urea. 1 It is also very slowly dissolved to some extent by normal salt 

 solution ; the solution is in all cases assisted by moderate warmth. Fibrin 

 obtained from venous blood is slightly more soluble in salt 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, 2 having heat coagulation temperatures of 55 and 75 respec- 

 tively. The latter, according to Halliburton, is reduced to 60-65 in 

 sodium chloride solutions, being 73-75 in magnesium sulphate solutions 

 only. Albumoses are also present in the fluid (Limbourg, Dastre). This 

 solution of fibrin in neutral salts occurs in the entire absence of putre- 

 factive decomposition (Green, Dastre). Fibrin swells in dilute acid (such 

 as 0*2 per cent. HC1) into a clear jelly, which very slowly undergoes 

 solution 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 globulins, one coagulating at 56 

 and the other at 75, and then becoming transformed into acid-albumin, pro- 

 teoses, and 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 

 H . . 6-83 



N 16-91 



S . . MO 



22-48 



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 amount 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, et 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, 

 Holzmaun, Arch, f, Physiol. , Leipzig, 1884, S. 210; and Arthus, " Coag. des liquides 

 organiques." Paris, 1894, pp. 105 et seq. 



2 Green, Journ. Physiol., Cambridge and London, 1887, vol. viii. p. 372. 



3 Hasebro'ck, 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., Strassburg, 1894, Bd. xix. S. 143. 



7 Hammarsten, ibid., Bd. xxii. S. 392. 



8 Sehafer, Proc. Physiol. Soc., Journ. Physiol., Cambridge and London, 1895, vol. 

 xvii. p. xx. 



