24 E. S. EDIE 



In later papers Fermi [1913, 1914] contests the theory that some proteo- 

 lytic enzymes have a specific action, and maintains that all proteolytic 

 enzymes have a general action on all proteins. 



Slight differences of behaviour of trypsin towards different proteins 

 under the same conditions have also been noted by Berg and Gies [1906], 

 Porter [1910], Long and Hull [1917], but not much importance seems to have 

 been attached to the facts. Others such as Glaessner and Stauber [1910] and 

 Auerbach and Pick [1912] find differences between the proteolytic and pepto- 

 lytic actions of trypsin, but in these cases possibly some of the action was due 

 to the pancreatic erepsin also. 



It seems to have been assumed, however, by all the authors quoted and 

 by others such as Hedin [1905] that try])sin is the enzyme responsible for the 

 digestion of fibrin and caseinogen, especially in experiments lasting only a 

 few hours. 



The action of alcohol on trypsin has been variously stated. Fermi and 

 Pernossi [1894] using Mett's tubes filled with gelatin found that in presence 

 of alcohol trypsin had more digestive action than in presence of water only. 

 The percentage of alcohol used is not stated. Chittenden and Mendel [1896] 

 found that the action of trypsin on fibrin was markedly inhibited by alcohol, 

 but did not test the action on any other substrate. Dastre [1896] found that 

 trypsin still digested fibrin and boiled albumin in presence of 15 to 20 

 per cent, of alcohol, while Gizelt [1906, 1, 2] states that 20% alcohol totally 

 inhibits trypsin. According to Bayliss [1915] trypsin will digest gliadin even 

 in presence of 80 % alcohol, the action in this case being due to the trypsin 

 in suspension. Vernon [1903, 1] noted that dilute alcohol had a considerable 

 inhibitory effect on the digestion of raw fibrin by trypsin. 



As dilute alcohol is frequently used in making extracts of various digestive 

 organs, it is important to know how the digestive action is affected thereby. 



1:; 



Experimental Details. 



The experiments were carried out as described previously [Edie, 1914]. 

 Ox fibrin after being finely minced and thoroughly washed was suspended in 

 water and gradually heated to 85°. The fibrin was then pressed dry and pre- 

 served in glycerol and a little chloroform until required. The caseinogen was 

 a 3 % solution in 1 % sodium carbonate. The pancreatic extracts were pre- 

 pared by finely mincing sheep's pancreas and extracting with chloroform 

 water for about a fortnight. The extract was then filtered and a little chloro- 

 form added as a preservative. 



The digestion was carried on at 37° in small flasks, a small measured 

 quantity of chloroform being added to exclude baeterial action in every case. 

 When fibrin was used, the amount of digestion was estimated by filtering off 

 the undissolved fibrin and determining the nitrogen in the filtrate by a 

 Kjeldahl determination. When caseinogen was the substrate, the amount of 



(220) 



