MR. A. J. EWART ON ASSIMILATORY INHIBITION. 409 
Tagre T. 
| 
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| After 30 minutes’ exposure. | After 1 hour's exposure. 
| =] 
Bryum Few leaves, and leaf-cells dead, | Most leaves and leaf-cells liv- | 
cespititium. | but rest living and assimi- | ing, and in all of these assi- | 
lating actively. milation is active, 
Orthotrichum | Most leaves and leaf-cells liv- | Many leaves and leaf-cells dead 
affine. ing and assimilation active, | andinlivingcellsassimilation 
| but a few leaves with plenty | faint or imperceptible. Inu 
of living leaf-cells show no | 5 h. rather weak, and in 1 
perceptible orextremely weak | day active assimilation in all 
assimilation. In 2-3h. many | living leaves. 
of these cells die, but the 
restshow normalassimilation. 
Dieranum | As in Orthotrichum. | Most leaves and leaf-cells liv- 
seoparium. ing and assimilation fairly 
active. Few leaves with all 
or many cells living, no assi- 
milation. Many of these 
die in from a few hours to a 
day, but in rest assimilation 
returns nnd isnormal in from 
5 h. to 1 day. 
Using strong solutions of ether and short exposures the stop- 
page of assimilation seems, especially with Bryum, to be almost 
immediately followed by the death of the cell, and hence in such 
cases it is diffieult to find living but non-assimilating cells. A 
series of more prolonged exposures were therefore made, the 
same plants being placed under bell-jars over a given quantity 
of a jl saturated watery solution of ether (1 part ether to 
100 H,O), the resulting atmosphere containing 1 volume of ether 
to from 15 to 30 of air, and hence sufficient to burn or form 
an explosive mixture. During prolonged exposures the atmo- 
sphere is renewed from time to time and fresh ether solution 
introduced. 
Table U shows clearly the pronouneed resistant power ex- 
hibited by Mosses to prolonged exposure to dilute ether-vapour, 
as well as the marked stoppage of assimilition which finally 
occurs. In Dicranum one result of prolonged exposure is that 
the protoplasm in many cases becomes darker, more greyish and 
opaque than normal; but this peculiarity is exhibited by cells in 
whieh assimilation is still present, and may remain for some 
time in cells to which the power of assimilation has returned. 
