574 DR. A. J. EWART ON ASSIMILATORY INHIBITION. 
window facing east to intermittent direct sunlight. As a result, 
the plants in a few days turned quite pale or white, and ap- 
peared to be dead. In this condition they remained exposed 
in a window facing north to diffuse daylight until, in spring 
1896, they began to show signs of life and new growth. Esa- 
mined in June 1896, the different parts varied, from white, 
pale green, yellowish or brownish green, to quite green in the 
young renovating parts. The latter are normal and show active 
assimilation. The older, perfectly white stems are dead and the 
cortical cells frequently come loose in loops, owing to the stem 
untwisting in such regions when the longer cortical cells come 
free from the shorter medullary cell. Such parts are dead. In 
many parts which, to the naked eye, appear white or only 
extremely faintly greenish, on examination the cells are found 
to be living and showing rotation. The chlorophyll grains have 
been killed and form separate irregular, colourless, faintly trans- 
parent polyhedral grains massed together, frequently in bands 
with clear spaces between, but in other cases entirely covering 
the inner surface of the cell-wall. 
Careful examination shows normal green, often brownish-green 
chlorophyll grains to be present between or generally within these. 
All conditions may be seen, from cells which contain 4 to 3 their 
normal amount of chlorophyll grains to ones in which only occa- 
sional scattered and pale or brownish-green chlorophyll grains are 
present, and the quantity of chlorophyll is less than 2 or 4 to 
Jy of the normal amount. The former cells show a fairly active 
evolution of oxygen, which in the latter is quite weak or faint, 
and can be seen to radiate from where the normal living chloro- 
phyll grains are present. These phenomena are shown best by 
the whorled leaflets from 0-5 to 1 em. long, composed of 3 to 6 
naked cells. The chlorophyll grains may form irregular masses 
containing several small starch grains, or may form short straight 
constricted chains of 4 to 8 chlorophyll grains joined together. 
In many of the living end-cells the chlorophyll is present almost 
entirely in this latter form, and is extremely scarce, the chloro- 
phyll grains, chains, or masses being separated by extremely 
large intervening clear spaces, and this although few or dead 
chlorophyll grains are present. Such cells show a weak but 
distinct evolution of oxygen, even though, as is often the case, 
the chlorophyll grains are brownish green in colour. No living 
cells entirely without living chlorophyll grains were found, 
