[Vol. 



820 ANNALS OP THE MISSOURI BOTANICAL GARDEN 



" diffusion-extract, ' ' described under ' ' carbohydrases, ' ' used 

 for action. The contents of the tubes were made neutral, 

 and acid and alkaline to N/200, as was done in the other pro- 

 teolytic experiments. Five drops of chloroform-thymol were 

 added as an antiseptic. Checks were set up containing the 

 gelatin together with 5 cc. of boiled " diffusion-extract." The 

 tubes were placed in an incubator at 35 °C. for a week, at which 

 time they were removed and cooled in running water. All 

 tubes hardened in a short time, showing that no hydrolysis 

 had taken place. 



General results for experiments on proteolysis. — The pro- 

 teolytic activity, although slow, as was the case with the 

 other enzymes investigated, is definite enough to warrant 

 the statement that proteinases and peptases are very gen- 

 erally present in the algae. When present, such enzymes 

 act best under neutral and alkaline conditions. This last 

 finding is interesting in the light of the existing differ- 

 ences of opinion regarding the relative value of acid and 

 alkaline substrates for vegetable proteinases. It will be re- 

 called that Vines ('97) found that acidity favored the pro- 

 teinase contained in the leaf pitchers of Nepenthes, and in a 

 later paper, he states that peptase (hydrolysing albumoses 

 and peptones to amino acids) always act best under faintly 

 acid conditions. Emmerling ( '02 ) , on the other hand, demon- 

 strated that the papain of Carica papaya acted more rapidly 

 when the substrate was alkaline. Euler ('12) states in a 

 general way that peptases require a neutral or faintly alka- 

 line substrate, and proteinases (tryptases) an acid one. 



Of the proteins employed, solutions of casein and peptone 

 prove the most favorable substrates. Albumin in solution is 

 acted upon slowly, but when employed in the form of Mett's 

 tubes, doubt exists regarding its digestion. Legumin appears 

 to be slowly hydrolysed by Enteromorpha and Chondrus, but 

 not by Mesogloea. Gelatin, either in the liquid state or in 

 the form of Mett's tubes, is not attacked. As groups, the 

 1 ' reds ' ' appear more active in proteolysis than do the 

 " greens," while, as was true for carbohydrases, the "browns" 

 show the least activity. 



