174 



acid reaction of the medium set in, caused a coagulum, formed in 

 a neutral medium, to disappear again. 



5. That the coagulum, mentioned sub 1 — 4, consisted of a sponge- 

 mass of fibres. 



From these experiments it might be concluded that a solution of 

 ordinary fibrin in strongly diluted NaOH, contained a substance 

 that could be obtained as a flake-like precipitate by an addition of 

 HOI, which precipitate was found to agglutinate in tibres a. at an 

 alkaline, />. at a neutral, c at a rather strongly acid reaction of the 

 medium; these fibres, in their turn, formed a net- or spongework, 

 a real coagulum, which coagulum could be dissolved in strongly 

 diluted NaOH and in strongly diluted acid. 



Further it appeared that this coagulum, formed at a neutral reac- 

 tion, not only dissolved again in a dil. NaOH-sol., but also that in 

 this solution a new coagulum could be obtained by neutralizing 

 this solution, and also by acidifying it rather strongly. And conver- 

 sely, if the coagulum was dissolved in strongly diluted acid, a 

 coagulum could be obtained from this solution by neutralizing it 

 with NaOH. 



It followed that we had to deal with a coagulating substance, 

 derived from tibrin, which could be made to pass from a sol-state 

 ii;ito a gel-state and back again. 



Now the question suggested itself what remarkable substance this 

 might be. 



Must it be assumed that the fibrin, when dissolved in NaOH, had 

 been decomposed, forming meanwhile a coagulable substr^nce hitherto 

 unknown, a substance derived from fibrin itself or from one of its 

 accompanying substances such as: blood-platelets, red and white 

 bloodcorpuscles ? 



Or might it be that the fibrin when dissolved in NaOH, had not 

 been decomposed, but had passed into a colloid solution, that there- 

 fore we might have to do here with tibrin in a sol-state, with an 

 alkali-hydro-sol of fibrin, from which state it might be brought 

 again into a gel-state by an action of acid, with or without the help 

 of a fibrin-ferment? 



It will be readily understood that I hesitated in making the latter 

 'supposition. First because it was diametrically opposed to the gene- 

 rally received opinion that fibrin must be looked upon as an irre- 

 versible gel. And secondly it seemed strange that fibrin coagulation 

 should take place in a strongly acid as well as in a neutral and 

 alkaline medium. 



