CHEMICAL BASIS OF THE ANIMAL BODY. 67 



temperature. The filtrate he dilutes with nine volumes of water and 

 to this adds gradually, and with continuous stirring, dilute caustic 

 soda until a permanent, flocculent and fairly copious precipitate is 

 formed. This precipitate carries the ferment down mechanically and 

 is finally washed, pressed, suspended in water, dissolved by acetic acid 

 to a neutral solution and dialysed till free from salt. 



For ordinary purposes an extremely active ferment solution may be 

 most readily obtained by Gamgee's method of extracting the so-called 

 'washed blood clot' with 8 p.c. solution of sodium chloride 1 . The 

 solution in this case contains a large amount of globulins in solution, as 

 also does the similar extract which may be equally efficiently prepared 

 from ordinary washed fibrin 2 . 



In no case as yet has the fibrin-ferment been obtained in a 

 condition of such purity as to justify any dogmatic statement as to its 

 chemical composition. All the solutions whose preparation has been 

 described above yield strong proteid reactions, and Halliburton 3 has 

 argued from his own experiments and a criticism of preceding work 

 that the ferment is really a proteid identical (?) with what he had 

 previously called ' cell-globulin ' (antea, p. 27). On the other hand 

 it is possible by appropriate methods to free the salt-extracts of fibrin 

 very completely from proteids without any great loss of ferment 

 activity, certainly without any such loss as would necessarily be the 

 case if the active substance were a globulin 4 . It may be said that the 

 apparent ferment-powers in such cases are in reality due to the presence 

 of calcium sulphate, which is now known to promote the clotting of a 

 dilute salt-plasma to an extraordinary degree 5 ; but as against this the 

 fact may be quoted that, solutions free from proteid reaction, and which 

 had been freed from salts by careful dialysis, lost their activity on heating 

 to 60 70, which they would not have done had the activity been due 

 merely to calcium sulphate. 



When Schmidt's method is applied to blood received directly from 

 an artery into an excess of alcohol no ferment can be obtained from 

 the precipitate thus obtained. It is hence evident that the living, 

 circulating blood contains no preformed ferment, and the question 

 thus arises from what does it take its origin during the clotting of 

 blood and presumably as an immediate antecedent to that clotting? 

 Buchanan held distinctly the view that the active agent in the whole 

 process was in some way connected with, if not derived from, the white 

 corpuscles, a view also held later on by Mantegazza. Schmidt also 



1 Gamgee, Jl. of Physiol. Vol. n. (1879), p. 150. 



2 Lea and Green, JL of Physiol. Vol. iv. (1883), p. 386. 



3 JL of Physiol. Vol. ix. (1888), p. 265. 



4 Lea and Green, loc. cit. 



5 Green, Ibid. Vol. vm. (1887), p. 354. 



e 2 



