432 MR. A» J. EWART ON ASSIMILATORY INHIBITION. 
of Dicranum, though no perceptible diminution of the stored! 
starch has taken place. After 3 days a fairly active power of 
assimilation is shown by all living leaves, and a perceptible 
diminution in the amount of starch present has taken place. 
If the same experiment be repeated with entire plants, after 
8 days nearly all adult leaves can no longer assimilate, but the 
young apical leaves still show a weak to fairly active power of 
assimilation. 
Experiments with Allium Cepa are interesting, because in this- 
plant the superfluous carbohydrate is stored not in the form of 
starch but of sugar. The leaves of Allium die rather readily 
when separated, and hence form unfavourable experimental 
material, but if the fully-developed flowering axis be cut off at 
its base, and the flower-head removed, the axis may remain living 
for weeks if the basal end be kept in water. Fehling's test shows: 
that in such a fresh flowering-axis traces of sugar are present in 
the outer assimilating layers, but much more in the inner 
parenchyma and abundance in the basal ith to jth of the 
axis. After being exposed to bright light for 8 days (base in. 
weak sugar solution) or 14 days (base in water), sugar is present 
in all cells and tissues and only a weak power of assimilation is- 
shown. After 10 days (base in sugar) or 14 days (base in 
water) all the cells are rich in sugar, and no evolution of oxygen 
is shown, though the cells are normal in appearance and the 
chlorophyll grains quite green and unaffected. After 2 days in 
darkness at 30? C. a very weak power of assimilation is shown, 
and plenty of sugar is still present in the inner parenchyma, but. 
much less in the outer green assimilating layers. After 4 days 
assimilation is moderately active, and a little sugar is still present. 
in the outer assimilating layers, but more in the inner paren- 
chyma. 
Plants of (Edogonium kept in water through which CO, is: 
occasionally allowed to slowly bubble, and exposed for several 
days to bright diffuse daylight, become packed with starch and 
show no power of assimilating except in a few cells, chiefly at 
the growing ends of the filaments, but also in intercalary cells, 
Which contain much less starch, and show a moderately active: 
evolution of oxygen. If the plants are now kept in darkness in 
well-aerated water at 20? C., after 5 days many filaments die, but 
most remain living, show a distinct reduction in the amount of 
starch present, and a fairly strong power of assimilation. 
