igisl Joseph Samuel Hepburn 145 



was used throughout each series of experiments, and the time of 

 digestion was noted. A glycerol extract of the gastric mucosae re- 

 quired 40 min. at 24° C, 100 min. at 8° C, and 230 min. at 0° C 

 An extract of the gastric mucous membrane in 0.25 percent hydro- 

 chloric acid sol. was more active, and required 20 min. at 24° C, 

 65 min. at 8° C, and 140 min. at 0° C, for digestion of the fibrin. 



Oguro (20) studied the influence of temp. as low as 0° C. on 

 the peptic digestion of ricin. From 0.05 to i.o cc. of o.i percent 

 sol. of pepsin was permitted to act on 2 cc. of 0.2 percent Suspension 

 of ricin in the presence of 0.5 cc. n/io hydrochloric acid sol.; the 

 total volume of the reacting mixture always being made 4.5 cc. by 

 dilution with water. The temp. of incubation were 38°, 20° to 21°, 

 8°, 5° and 0° C. The progress of digestion was followed by noting 

 the degree of cloudiness of the Suspension from time to time, the 

 results being recorded as " clouded," " a little clouded," " traces of 

 cloud," " almost clear," " nearly clear," " clear." The pepsin di- 

 gested the ricin at all the temp. of incubation, gradually producing 

 a clear Solution, although the digestion proceeded more slowly at the 

 lo wer temp. Thus, when o.i cc. of the pepsin sol. was used, the 

 ricin Suspension became clear after 50 min. at 38° C, 50 min. at 20° 

 to 21° C, or 24 hr. at 0° C, while merely a trace of a cloud re- 

 mained after incubation for 2 hr. at 8° C, or for 2 hr. at 5° C. 



Trypsin. Müller (15) prepared a glycerol extract of trypsin 

 from the intestinal tracts of carp, a fish which is without a stomach 

 and secretes no peptic enzyme. Pieces of nutrient gelatin of equal 

 size, and fibrin particles, were used as Substrates. A given volume 

 of the trypsin sol. dissolved the piece of gelatin after incubation for 

 2}i hr. at 20° C, 16 hr. at 8° C, or 34 hr. at 0° C. The fibrin 

 particles (100 mg.) were dissolved by a given volume of enzyme ex- 

 tract after digestion for 5^ hr. at 20° C, 31 hr. at 8° C, or 72 hr. 

 at 0° C. The trypsin, therefore, showed a distinct activity at 0° C. 



Galactase. Babcock (21) and his collaborators (22) have 

 demonstrated the activity of galactase, the native trypsin-like, pro- 

 teolytic enzyme of milk, during the ripening of Chedder cheese at low 

 temp. Fresh Cheddar cheese were carried at a temp. of 25 to 30° F. 

 for periods of 14 and 17 months. Progressive increase occurred 

 in the total soluble nitrogen of the cheese during holding. In 

 another series of experiments, Cheddar cheese were manufactured 



