85 
Green. — On Vegetable Ferments . 
Krauch 1 proved its existence in leaves and shoots, Bara- 
netzky 2 in buds and in potato-tubers. Recently Wortmann 3 
has denied its existence in leaves, attributing the conversion of 
starch into sugar to the direct influence of the protoplasm of 
the cells. Its existence there has however been reaffirmed by 
Vines 4 and others, who have criticised Wortmann’s results. 
It has been found by the writer in the pollen-grains of 
several plants 5 . 
This body has been investigated in gradually maturing 
seeds of barley by Brown and Morris 6 , who show that it 
makes its appearance in the developing grain at a very early 
period and gradually increases until the endosperm is fully 
developed, but the grain not ripened. Comparing the amount 
formed at three periods, when the endosperm is half-developed, 
when it has attained two- thirds of its development, and when 
it is complete, they find the relative quantities may be repre- 
sented by the figures 4*4, 7-8, and 9*9. It is most plentiful 
always in the part of the endosperm nearest to the young 
embryo and appears to prepare the material for the nutrition 
of the latter as it is increasing in size. On germination, some 
time later, the diastase appears in the young embryo, both in 
the plumule and the radicle, though here the quantity is rela- 
tively small. 
Its action may be examined upon the starch-grains in 
situ , or it can be extracted by water or glycerine, and its 
activity noted upon starch-paste, or on a preparation of 
soluble starch. In the former case Brown and Morris describe 
it as gradually dissolving the starch-grain from the outside 
only, without giving rise to any pitting or corrosion, the size of 
the grain gradually diminishing, while the shape and trans- 
lucency are unaffected almost to the point of disappearance. 
When a weak starch-paste, containing about 1 per cent, of 
starch, is mixed with an extract of this form of diastase, it 
1 Landwirthsch. Versuchsstat. XXIII, 1879. 
2 Die starkeumbildenden Fermente, 1878. 3 Bot. Zeitg., 1890. 
4 Brit. Assoc. Reports, Cardiff, 1891 : also Annals of Botany, V. 
5 Ibid. 6 loc. cit. 
