126 Green. — On Vegetable Ferments. 
composition of invertase, in the course of which they suc- 
ceeded in obtaining it perfectly pure, and in investigating the 
products of its decomposition. They conclude from their 
investigations that this enzyme is a member of a homologous 
series of bodies to which the name the inver tan-series is given. 
The series consists of seven members, a, (3, y , 5, e, C and r/ 
invertan, which differ from each other in the proportion of 
nitrogen which they contain and in their optical activity. 
The highest member of the series, a invertan , is a more 
stable body than the remainder and is insoluble in water. 
The remaining six are freely soluble, the solutions being clear 
but rather viscous ; they do not coagulate on heating. They 
all agree in being colourless when dissolved, in not dialysing 
and not crystallising. When alcohol is added to alkaline or 
neutral solutions the latter become milky and the cloudiness 
is not removable by filtration. Acids added to the milky 
liquid cause precipitation. With copper-oxide in alkaline 
solution, and in the presence of caustic potash, they all give 
precipitates which are very bulky and almost mucilaginous. 
Invertase itself, the authors consider to be the second member 
of the series, (3 invertan , and on its decomposition it splits up 
into the first and fourth members, the former containing more 
and the latter less nitrogen than invertase. Their views of 
the composition of the members of the series are, that with 
the exception of the lowest they are all combinations of a 
peculiar proteid yielded by the yeast-cells, to which they 
give the name yeast albuminoid , with the lowest member, 
y] invertan , and that the latter body is itself probably a com- 
bination of the same proteid with a carbohydrate, eighteen 
parts by weight of the latter uniting with one part of the 
albuminoid. A full discussion of their views will be found 
in their paper alluded to 1 . 
Action of the Enzymes. 
The action of these enzymes seems in nearly all cases to be 
one of hydration, myrosin so far being the only exception. This 
is undoubtedly the case in the simplest transformations. 
1 Journ. Chem. Soc., No. CCCXXXV, Oct. 1890, p. 835. 
