128 Green.— -On Vegetable Ferments. 
be taken and mixed with twice their weight of acetic anhy- 
dride, the mixture then heated for a long time to 8o° C., and 
finally the excess of acetic anhydride distilled off and the 
residue dialysed, it is found to be changed into a proteid 
that is not diffusible, is soluble in dilute alkali, is precipitated 
by acetic acid and potassic ferrocyanide, and by many metallic 
salts, as ordinary proteids are. According to Hofmeister a 
similar effect may be produced by prolonged heating to 
] 40° C. The resulting brown mass contains a part soluble in 
water and another not so, which react after the manner of a 
globulin and a derived albumin respectively. 
Other views of the relationship have been advanced, some 
observers believing that peptones are isomers of proteids. 
Adamkiewicz suggests that they differ in the removal of 
salts, and a re-arrangement of the molecule. The most 
recent hypothesis was put forward by Schiitzenberger 1 last 
year. He holds that peptone is a mixture which, by treat- 
ment with phosphotungstic acid, can be separated into two 
parts, one containing a little more oxygen than the other, 
and both being urei'de bodies. Fibrin, on the other hand, is a 
kind of compound ether, which is saponified by the enzyme 
and in taking up water splits into the two bodies found. 
The transformation is thus one of hydration, being the result 
of the decomposition of an ether by saponification. 
The action of an enzyme appears to differ in no way from 
an ordinary chemical reaction. Most of the changes that are 
brought about by such bodies can be effected in the laboratory 
by ordinary chemical processes, starch being hydrolysed to 
sugar by dilute mineral acids, fats split up by alkalis or super- 
heated steam, peptones formed by heating proteids to high 
temperature in a Papin’s digester. Invertase has been 
specially investigated by O’Sullivan and Tompson 2 , who find 
that the rate of inversion of cane-sugar by it may always be 
represented by a definite time-curve which ‘ is practically that 
given by Harcourt as being the one expressing a chemical 
change of which no condition varies excepting the diminution 
1 Comptes rendus, CXV, p. 768. 2 op. cit. p. 926. 
