THEORIES OF COAGULATION. 173 



residue after gastric digestion of its solution, showing that it at least, 

 as above stated, contains some nucleo-proteid. Probably this is an 

 accidental contamination. 



Production of intravascular coagulation of Hood and of uncoagulable 

 blood. It was discovered by Edelberg 1 that intravenous injection of 

 Schmidt's fibrin ferment may produce thrombosis in the vense cavae, 

 the right side of the heart, and the pulmonary arteries. Foa and 

 Pellacani 2 showed that the same will occur with extracts of various 

 organs. The same fact was independently noticed by Wooldridge, 3 

 who found that a substance or substances obtainable from saline extract 

 of lymphatic glands, thymus, testicle, and other glandular organs, tend to 

 produce, when injected rapidly in sufficient amount into the veins of 

 animals, instant coagulation of the blood whilst still within the blood 

 vessels. On the other hand, if injected more slowly, or in insufficient 

 amount to produce intravascular coagulation, the coagulability of the 

 blood in vitro becomes abolished ; this condition was termed by Wool- 

 dridge the " negative phase." When the negative phase is once obtained, 

 a very large dose of the material fails to produce intravascular clotting. 4 

 Wooldridge gave the name " tissue fibrinogens " to the substances thus 

 extracted, and more extended knowledge has led to the general recog- 

 nition of the fact that they belong to the class of nucleo-albumins or 

 nucleo-proteids. The coagulation when it occurs is found, first, in the 

 portal venous system ; then in the general venous system, and pulmonary 

 arteries and in the right side of the heart ; and finally, when the effect 

 is most pronounced, in the general arterial system ; but rarely in the 

 pulmonary veins. Its occurrence is assisted by an excess of C0 2 in the 

 blood. 5 Albino rabbits and the Norway hare in its albino condition are 

 immune to these effects (Pickering). 



It has been supposed by Lilienfeld that this action of the nucleo- 

 proteid in causing coagulation is due to the nuclein or nucleic acid 

 which it contains, and that, when the negative phase is obtained, this 

 result is due to the action of the proteid part of the molecule of 

 nucleo-proteid in preventing coagulation. This hypothesis is rendered 

 improbable by the observations of Halliburton and Pickering, 7 who 

 found that intravascular coagulation can be readily obtained in rabbits 

 by intravenous injection of artificial colloids (containing no nucleic 

 acid). 8 These colloids likewise yield the negative phase (retardation of 

 coagulation), if injected in quantity insufficient to produce coagulation ; 

 and, as with solution of nucleo-proteids, they are without action upon 

 albino rabbits. Nevertheless, like solutions of nucleo-proteid, they 

 hasten the coagulation of the blood of other animals, if mixed with it 

 in vitro. These observers also found that the retarding influence of 



1 Arch. f. exper. Path. u. PharmakoL, Leipzig, 1880, Bd. xii. S. 283. 



2 Riv. din. di. Bologna, 1880, p. 241. 



3 Proc. Roy. Soc. London, 1886. See also ''Die Gerinnung des Blutes," Leipzig, 1891. 



4 Wooldridge, Arch. f. PhysioL, Leipzig, 1888. 



5 Wright, Journ. PhysioL, Cambridge and London, vol. xii. 6 Loc cit. 



7 Journ. PhysioL, Cambridge and London, 1895, vol. xviii. pp. 54 and 285 ; Pickering, 

 Proc. Roy. Soc. London, 1896, vol. Ix. p. 337. 



8 The artificial colloids investigated were prepared by Grimaux's methods (Compt. rend. 

 Soc. de bioL, Paris, 1881, tome xciii. p. 771 ; 1884, xcviii. pp. 105, 1434, and 1578). 

 Their chemical properties and mode of preparation have already been described by Professor 

 Halliburton in a previous article (p. 36). It is possible that they may act, not directly, 

 but by setting free nucleo-proteid from the white corpuscles. Their solutions do not, 

 however, cause disintegration either of the red or white corpuscles, nor any apparent 

 change in the epithelium of the vessels. 



