562 DR. A. J. EWART ON ASSIMILATORY INHIBITION. 
In another grass, Phalaris canariensis, though the seed is 
smaller and the store of nourishment is less than in the above 
cases, nevertheless in some of the young etiolated leaves a faint 
power of assimilation can be detected, and this is also the case 
with the cotyledons of etiolated seedlings from certain plants 
with oily and large or small seeds. 
Phalaris canariensis.—(a) Stems 11-12 em. long, reddish sheath (red sap) 
enclosing central yellow leaf, tip projecting for 3 to 1 em., and showing 
very faint or no assimilation. After 1 day's exposure to light this leaf 
has turned green and shows fairly active evolution of O. (^) In plants 
larger than (a) the leaf-tip beginsto wither and shows no assimilation. 
Linum usitatissimum and Brassica Napus.—Cotyledons fairly deep yellow. 
(1) Cotyledons still packed with oil or starch. Evolution of O extremely 
faint or imperceptible. (2) Cotyledons, starch or oil much reduced, but 
a fair amount still present; weak but quite distinct evolution of O. 
(3) Later. Cotyledons starved, still yellow, but no assimilation. 
Ricinus communis.—(a) Stem 25 em. Cotyledons 3 by 2 cm., quite yellow 
oil-drops in cells but not many, show quite distinct but very weak evolu- 
tion of O. (b) 5 days later cotyledons yellow and of same size, but no 
assimilation shown. In light are in 2 days fairly green and show mode- 
rately active assimilation. 
Further experiments were performed with plants having bulbs 
or root-stocks containing a large store of nourishment, so that 
the plants could be kept living for months in continuous 
darkness. 
Beta vulgaris.—(a) Etiolated leaves 10 em. long, lamina 3 by 2 em.  Chlo- 
roplastids small and pale yellow ; very weak but quite distinet evolution 
of O. (b) Leaf 15 cm., lamina 5 by 2cm. Petiole and ribs reddish, 
lamina yellow, cells clear and transparent, ehloroplastids small and pale 
yellow; very weak evolution of O. (c) Leaf 28 cm., lam. 5 by 2 cm., 
paler. and chloroplastids smaller and paler than when younger. No 
evolution of O. The best stock contains plenty of nourishment and on 
bringing the plants into light such leaves remain living, the lamina 
broadens and turns slowly green, and as it turns green commences to 
evolve O (distinct evolution of O in 3 days). 
Hyacinthus.—(a) Leaves 15 em. long, 2:5 broad, deep yellow at apex and 
edges, paler in middle and quite pale at base. Chloroplastids fairly large 
and yellow ; distinct but very weak evolution of O. (b) 2 months later. 
Leaves 30 to 35 em. long, lower half white, upper yellow, but showing no 
power of assimilation. In light the upper halves of the leaves take from 
1-2 weeks to become thoroughly green and the basal parts are then still 
pale. After 1 week green to greenish-yellow parts show a moderately 
active evolution of O. 
Allium Cepa.—Gives similar results to Hyacinthus, but the leavesdo not live 
so long in darkness, are much branched and somewhat contorted, and the 
apical portions only are yellow. 
— 
