262 



Dr. L. C. Wooldridge. On the 



[Apr. 16, 



very long standing no increase takes place. If, however, after the 

 removal of the slight clot, the plasma be diluted with four times its 

 volume of water, it clots through and through. 



Now 4 or 5 per cent, solution of salt does not interfere with the 

 action of the fibrin ferment, and hence we must conclude that as in 

 peptone plasma, so in salt plasma, the bulk of the coagulable matter 

 is not in the form of fibrinogen, but as a substance which must first 

 be altered by dilution. 



These conclusions are confirmed by the behaviour of the plasma on 

 heating. As is well known, solutions of Hammersten's fibrinogen 

 coagulate on heating to 54 — 56° C. 



If some NaCl plasma which has been treated with ferment, and 

 from which the slight clot thereby caused has been removed, be heated 

 to 56°, it remains perfectly clear ; long exposure to this temperature 

 does not alter it, and it can be heated up to a very high temperature, 

 90° and upwards, without the slightest coagulum forming, though 

 at high temperatures it becomes opalescent. 



The exact upper limit of coagulation varies ; it is usually over 90° C. 

 Of course if haemoglobin be present, it interferes with the experiment. 

 Now it will be remembered that this plasma, in spite of the removal 

 of the small quantity of fibrin, contains a large quantity of fibrin- 

 yielding matter. 



The fact that ferment gives a slight clot in Nad plasma may be 

 taken as an indication that NaCl plasma does contain a certain small 

 amount of true fibrinogen, and in fact if NaCl plasma which has not 

 been treated with ferment be heated to 56°, it becomes turbid, and a 

 slight coagulum forms. This, like the clot obtained by ferment, is 

 sometimes very small indeed, sometimes more considerable. 



Before describing the behaviour of peptone plasma on heating, I 

 must make a slight digression. 



In my note previously referred to,* I showed that there exists 

 dissolved in the plasma a body separable by cooling. So long as this 

 body is present, coagulation is produced by passage of a stream of 

 carbonic acid through the plasma, the whole of the coagulable sub- 

 stance being converted into fibrin. At the same time not only is 

 fibrin ferment produced, but also a body capable of converting the 

 coagulable body of the plasma into fibrinogen. To make this perfectly 

 clear, I shall give an example. 



Peptone plasma, rich in the substance separable by cold, is treated 

 with C0 2 ; it coagulates, the serum is pressed out from the clot and 

 allowed to stand, when it again becomes alkaline. On adding some 

 of this serum to a new portion of plasma, the latter clots completely 

 and with great rapidity. The clotting is much more rapid than the 

 original clotting with C0 2 . 



* " On a New Constituent, &c," ante, p. 69. 



