62 THE GELATIN FROM WHITE 



0.25 per cent solution of sodium carbonate; 300 c. c. of a 

 powerful pancreatic juice, prepared from Kiihne's dried 

 pancreas, added, and the mixture warmed at 40 C. for five 

 days, thymol being added from time to time to prevent 

 putrefaction. In an alkaline pancreatic juice of this description 

 the pieces of tendon swell up and the individual fibers become 

 more or less separated, so that the mass becomes soft and 

 spongy, thus giving the solvent a good opportunity to reach 

 every part of the tissue. 



As has been frequently demonstrated,* collagenous fibres 

 which have not been boiled with water or treated with dilute 

 acid are insoluble in an alkaline solution of trypsin. Elastic 

 fibres, on the other hand, undergo digestion by this treatment, 

 with formation of soluble products, elastoses and elastin- 

 peptone. Mucin is likewise dissolved by the alkaline fluid, 

 while all albuminous matter is readily converted into soluble 

 proteoses, peptone, and amido-acids. This method would cer- 

 tainly seem to furnish an effectual means of removing all tissue- 

 elements except the collagen; even the nucleo-proteids and 

 nucleins of the tissue cells being dissolved by this treatment. 



When the digestion was completed the residual collagen was 

 strained off and washed thoroughly in large volumes of water 

 until the pieces of tissue were without action on litmus paper 

 and the fluid gave no reaction for dissolved proteids. It is 

 to be noted, however, that when such apparently neutral 

 tissue is boiled with water, the fluid gradually acquires an 

 alkaline reaction, thus indicating that the last traces of alkali 

 cannot be removed by water alone. The collagen was next 

 boiled with several liters of water, each portion of water added 

 being kept in contact with the collagen for a few hours only, 

 in order to avoid the formation of any gelatoses by the too 

 prolonged heating of the newly formed gelatin. For the same 

 reason water was frequently added to prevent the boiling 

 point of the solution being raised by the increasing concen- 

 tration. When the first extract was poured off, the residual 



* See Ewald, Zur Histologie und Cbemie der elastischen Faeern und des 

 Bindegewebes. Zeitschr. f. Biol., Bd. xxvi, p. 1. 



