418 



Dr. L. C. Wooldridge. 



[Mar. 6, 



I. A measured quantity of blood was received directly from the 

 carotid of a dog into a vessel containing an equal bulk of a 10 per 

 cent, solution of common salt, great care being taken that the com- 

 plete admixture of the blood and salt solution was effected as rapidly 

 as possible. By the help of the centrifugal machine plasma was sepa- 

 rated from this " salted blood," and this plasma was again subjected 

 to the action of the machine until all traces of formed elements were 

 removed. As is well known, a portion of such a plasma diluted with 

 five times its bulk of water coagulates rapidly, whereas the undiluted 

 plasma remains liquid for an almost indefinite time. 



According to commonly received opinions, such a " salted plasma " 

 contains all the fibrin factors, including the ferment, the latter having 

 already passed out of the cells into the plasma ; and the reason given of 

 the absence of coagulation in such a salted plasma and its occurrence 

 upon dilution is, that the presence of the salts presents a hindrance to 

 the action of the fibrin ferment, and that this obstructive influence of 

 the salt is removed by the dilution of the mass. 



~No one, however, as far as I know, has taken the trouble to ascer- 

 tain whether fibrin ferment is present in such salted plasma. And, 

 as a matter of fact, it is not ; whereas it does make its appearance as 

 soon as dilution with water has taken place, as the following experi- 

 ment shows : — 



A portion of the undiluted salted plasma was treated with absolute 

 alcohol in large excess, and the precipitate after being allowed to 

 remain under the alcohol for three or four weeks was dried at a low 

 temperature and extracted with water — that is to say, the plasma, 

 was treated in the way usually adopted for obtaining a solution of 

 ferment fairly free from proteids, &c. A portion of the diluted 

 plasma, or rather of the serum resulting from the coagulation of the 

 diluted plasma, was treated in an exactly similar manner. 



The aqueous extract of the diluted plasma brought about coagula- 

 tion in specimens of magnesium sulphate plasma (such as is usually 

 employed for testing the presence of fibrin ferment) in from ten to 

 fifteen minutes. The aqueous extract of the undiluted plasma brought 

 about no coagulation in specimens of the same magnesium sulphate 

 plasma, even after the lapse of eighteen hours. 



The conditions of each experiment were made as exactly alike as. 

 possible ; and the conclusion seemed inevitable that ferment is present 

 in the diluted and coagulated plasma, but absent from the undiluted 

 plasma. 



This conclusion is, moreover, supported by the following experi- 

 ments : — To a portion of the undiluted plasma above mentioned a 

 small quantity of fibrin ferment was added, in the form of the dried 

 precipitate thrown down by alcohol, i.e., a mixture of coagulated 

 proteids and ferment. Coagulation took place. I have no record of 



