MR. A. J. EWART ON ASSIMILATORY INHIBITION. 385 
the second appears to be shown by the following data:—The 
upper leafy portions of the stems of Dicranum scoparium are kept 
air-dried for 3 months at 18° C. to 20°C. The leaves and leaf- 
cells are for the most part living, and on making cell-preparations 
with Bacteria show as soon as examined an active evolution of 
oxygen, t. e., the absorption of water is almost immediately fol- 
lowed by a resumption of assimilation even after so long a dormant 
period. A sample of such dried plants contained 8:18 per cent. 
of water (calculated by keeping a known weight in a CaCl, 
desiccator at 100^ C. to 105° C. till no further loss of weight 
takes place). After drying in desiccator for several days, until 
the weight shows no further appreciable diminution, the plants 
still contained 1:78 per cent. of water. 
Another sample of fresh plants contained 53:7 per cent.; after 
being air-dried for a few days contained 15:88 per cent.; after 
being in a desiccator at 35° C. till the weight remained constant, 
contained 2:07 per cent. of water. 
Plants of Cladonia rangiferina kept air-dried for 3 months at 
15° C. to 20° C. are almost unaffected, the gonidia being almost 
all living. If moistened and rapidly examined, at first no per- 
ceptible or a mere trace of an evolution of oxygen is shown, 
but this after 4 hour is moderately active and in 1 hour is quite 
active. The plants contained 14°55 per cent. of water; after 
being kept for 1 day at 45? C. they contained 6:9 per cent., after 
2 days 6:84 per cent., after 3 days 6°76 per cent., and after a 
4th day at 50° C. 5:56 per cent. 
On comparing these results with those in Table D, it can at 
once be seen that there is a distinct relation between the degree 
of desiccation and the inhibitory after-effect produced upon 
assimilation. The relation between the two is, however, by no 
means proportional, and whether it is causal or merely accidental 
it is impossible to say. 
Effects of Moist Heat. 
Itis well known that at a certain maximal temperature a chloro- 
phyllous cell or tissue ceases to assimilate. Thus with Aspidium, 
Mimosa, Chara, Elodea, and various Mosses at a temperature of 
from 37? C. to 39? C., though exposed to optimal illumination, no 
evolution of oxygen ean be detected by the Bacterium method. 
lt is of course always possible that assimilation may continue at 
temperatures considerably above those at which any evolution of 
