130 Green. — On Vegetable Ferments. 
to proteoses, peptones and amides ; emulsin to several bodies 
of which glucose is one. Though there is but little direct 
evidence to establish this hypothesis, certain facts that have 
been noticed lend a certain support to it. O’Sullivan and 
Tompson 1 , in tracing the action of heat on invertase, found 
that this varies greatly according to the presence or absence 
of cane-sugar in the experiments. When no cane-sugar was 
present, the enzyme was almost all destroyed by heating to 
50° C., while in its presence this effect was not produced till 
the temperature was 75 0 C., a difference of 25 0 C. The authors 
advance as a possible explanation the view that the invertase 
enters into combination with the sugar, and that the resulting 
body can resist the heat more successfully than the invertase 
alone. They hold that the combination is broken up when 
the compound molecule meets with another molecule of cane- 
sugar. A fuller discussion of their hypothesis will be found 
in their paper already alluded to 2 . 
Bearing on the same point is Chittenden’s observation 3 
that if neutralised pine-apple juice be heated to 6o° C. in the 
absence of any proteoses or peptones, the ferment is rapidly 
destroyed, whereas this temperature is the one at which the 
enzyme is most active if proteids be present during the 
heating. Biernacke 4 found similarly that albumoses or 
peptones raised the temperature at which trypsin is destroyed 
by five degrees or more, and that while pepsin in the absence 
of peptone was destroyed in acid solution by a temperature of 
55 0 C. it was active after being heated with peptone to 70° C. 
We may note in this connection too the possible significance 
of the inhibitory effects of traces of acid or alkali in the 
solution in which the enzyme is working. The minute trace 
of the reagent seems to correspond to the extremely small 
amount of the enzyme usually present, and it is at least 
possible that it may work by entering into some combination 
with the latter, the body formed not being capable then of 
uniting with the substance which the enzyme would ordinarily 
1 op. cit. p. 900. 2 op. cit. p. 919. 3 op. cit. p. 17. 
i Zeitschr. fur Biol., Band XXVIII, p. 49. 
