93 
Green. — On Vegetable Ferments . 
cent, the speed of the hydrolysis is reduced by one half. The 
ferment is precipitated uninjured by 47 per cent, of alcohol, 
but a larger proportion decomposes it, as when the resulting 
precipitate is redissolved it is found to be inert towards 
sucrose. 
The optimum temperature for the action of invertase is 
between 55 and 6o° C. At 65° C. it is gradually and at 75 0 C. 
rapidly destroyed. Below the optimum temperature the 
activity gradually diminishes. 
Invertase works best in a cane-sugar solution of the con- 
centration of about 20 per cent., the activity being slightly 
lessened as the sucrose is increased in amount to 40 per cent., 
while in saturated solutions inversion proceeds very slowly. 
The products of the inversion seem to have no inhibitory 
influence on the working of the enzyme, a point in which it 
forms an exception to the general rule. It is not exhausted 
by its activity. 
Fernbach 1 noted that his extract from Aspergillus was less 
active in light than in darkness, and that the inhibitory effect 
was the greater as the extract was made gradually more acid. 
Cyto-hydrolytic Enzymes. In the endosperms of the Palms 
the carbohydrate reserve materials take the form of cellulose, 
the walls of the cells being so enormously thickened that their 
cavities seem to be almost obliterated. As these walls gradually 
disappear during germination it seems probable a priori that 
the seeds contain an enzyme for its transformation into some 
soluble product. Many observers have endeavoured to detect 
the presence of such a body, either in the embryoes or the 
endosperms of various species, but hitherto without success. 
Most experiments have been conducted on the seed of the 
date ( Phoenix dactylifera). The well-known figure in Sachs’ 
text-book accurately represents the various stages in the 
growth of the embryo, part of the cotyledon of which is 
transformed into an absorbing organ, or haustorium, which 
gradually softens, corrodes, and dissolves the hard cellulose of 
the endosperm. A section of this haustorium shows it to be 
1 loc cit. 
