54 
MR. J. R. GREEN ON THE CHANGES IN THE PROTEIDS 
fibrin. This was precipitated on neutralisation, and was soluble in weak acids and 
alkalis. No doubt part of it was due to the action of the acid present, for a control 
tube, with acid only and no ferment, showed the formation of some, though not so 
much. The appearance of this body always struck me as peculiar, as, according to 
Kuhne’s theory of proteolysis, hemialbumose is not an antecedent of such a body, 
but is converted at once into peptone. To this point I shall return later, merely 
noting here that the occurrence of the acid-albumin made me particular to see that in 
later experiments there was no proteid subjected to the action of the ferment but the 
albumoses, and then, as before, I always found this neutralisation precipitate present. 
Shortly after this body had appeared the existence of true peptone was recognisable 
in the dialysate by the biuret reaction. I never found the dialysates give this unless 
ferment was present in the digesting mixture. The HC1 alone had the power of 
producing the acid-albumin, but could take the digestion no further, or at most could 
produce only the merest trace of peptone. 
In many cases there was mixed with the solution of the albumoses a small amount 
of a peculiar colouring matter, which, on the addition of caustic soda, gave a strongly 
marked yellowish-brown tinge to the liquid. The biuret reaction was consequently 
not very easily noted. I therefore adopted another test for peptone, which I 
found to be exceedingly delicate.* It consists in freeing the solution from all other 
proteids by boiling with freshly prepared ferric acetate and then adding to it acetic 
acid and a drop of metatungstic acid. Any peptone, which may be present, is thereby 
precipitated in a finely granular form. By this reaction I was able to find traces of 
peptone which were not discoverable by the biuret reaction, for the reason already 
stated. I tested the controls always by this method, at the same time as the 
dialysates of the proteids with ferment present, and found, as indicated by the 
biuret, where practicable to apply this, that a large quantity of peptone was formed 
by the ferment, and the merest trace only by the HC1. 
With much more trouble I succeeded in showing that the ferment produced 
crystalline bodies, showing crystals similar to those already alluded to as being- 
formed during the digestion of fibrin. In some cases these were mixed with other 
crystals, resembling those of asparagin, and in yet other cases the latter were by far 
the most numerous. These were deposited, on concentration of the dialysates and 
evaporation on glass slides. There was a difficulty in satisfying myself for some time 
that the crystals really came from the proteids in consequence of digestion, as my 
ferment extracts, being glycerine extracts of the germinating seeds, might have con¬ 
tained some of these bodies, although they had been themselves dialysed. Several 
experiments were therefore conducted to settle the point. In one series of these the 
dialysates were changed several times and the quantity of crystals obtainable from each 
observed. The fifth dialysate contained them in greater quantity than the first, which 
indicated a formation of them as the digestion proceeded, for if they were in the 
* Martin : Op. cit. 
