if to this fibrin-orthophosphoric aeid-solntion-strongly diluted NaOH 

 was added, so that the fluid became about neutral, a very thin haze 

 was formed, whicii after some time was found to consist of very 

 fine threads which were dissolved again by the addition of some 

 more NaOH. If, liowever, the latter solution was neutralized again 

 by diluted acid, the coagulum of fibres appeared again ; we evidently 

 had to do here with a reversible process. The fibres were also formed 

 if to the fibrin-orthophosphoric-acid-solution di- or trinatriumphos- 

 pliate were added, both, alkaline solutions as we know. 



If now the coagulum caused by Na,HPO, or by NajPO^ in a 

 fibrin H^PO^ solution was thoroughly washed in water and exposed 

 again to strongly diluted HjPO^, the coagulum was dissolved again, 

 whilst an addition of Na^HPÜ^ or NajPO^ again effected a coagulum. 



Secondly some results may be mentioned, obtained in experiments 

 with solutions of pure fibi-in in strongly diluted NaOH. 



Neutralization with diluted H3PO4 first caused a hazy precipitate 

 which turned into fibres. With various other acids the same results 

 were obtained. An addition of somewhat too much acid, so that 

 the fluid became distinctly acid caused the coagulum to pass into 

 solution again; it could, however, be produced again by neutralizing 

 this solution. 



If to a solution of pure fibrin in 0.1 7„ NaOH drops of NaH.PO,, 

 which as we know gives an acid reaction, were added, a precipitate 

 was formed which, often after a few minutes already, passed into 

 a network of fibrils. 



Here too it could be observed that whilst at first the fibrous 

 substance was distributed over the whole fluid, after some time the 

 coagulum settled upon one of the sides of the test-tube, whence we 

 may conclude that the coagulum must possess the power of retraction. 



If this coagulum, after being washed with water, was exposed to 

 a 0.1 7o NaOH-solution it was dissolved again, while the addition 

 of an acid or of an acid phosphate of Na brought out again a very 

 fine coagulum of fibres, often after only a few minutes. 



Acid phosphate of Ca was found to effect coagulation in fibrin 

 NaOH-solutions under the same circumstances as acid phosphate of 

 Na. To a certain extent there was a difference, however, as the 

 coagulum, obtained by acid phosphate of Ca, even after being washed 

 thoroughly, did not dissolve so easily in dil. NaOH as the coagulum 

 caused by acid Na-phosphate. 



It seemed interesting to find out if a weak acid such as CO3 

 would act in a similar way on fibrin-NaOH solutions, as the other 

 acids and acid salts, mentioned above. And it appeared indeed that 



