406 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
transparent, and in Dicranum without oil-drops. After 2 or 3 
days’ exposure to light, the plants are quite normal in all respects. 
The slight yellowish tinge acquired by the chlorophyll grains and 
the starvation phenomena exhibited are therefore results of the 
absence of light. 
Table S (p. 407) gives the results of keeping the mosses for 
long periods in darkness in an atmosphere of CO,, temperature 
averaging 15° C. 
It is worthy of remark that in many cases, after prolonged 
exposure, cells which show no assimilation do not recover that 
function even though they may remain living and plasmolysable 
for 2 or 3 days. Such cells have permanently lost the power of 
assimilation and are, as long as they live, nourished as a non- 
chlorophyllaceous cell is, though to all outward appearance the 
chlorophyll-apparatus is normal and intact. Attempts were 
made to keep such cells living by supplying them with artificial 
nutrient media, but without success. Apparently when asphyxi- 
ation produces a permanent stoppage of assimilation, it involves 
internal changes exercising so profound an influence upon the 
vitality of the cell that sooner or later death follows as a necessary 
consequence. 
In Dicranum the sequence of changes from life to death are :— 
The protoplasm gradually becomes more opaque, granular, and 
greyish, and also less readily plasmolysable, assimilation becomes 
weaker and weaker and finally stops; in this condition the cell 
may remain with the chlorophyll grains green and unaltered for 
a few days; in the first stages assimilation can return and the 
cell become normal again, but in the later stages the power of 
recovery is totally lost, and this is finally followed by the 
shrinking of the protoplasm from the cell-wall, the chlorophyll 
grains turning first yellowish and then rapidly losing all colour, 
until finally the cell-cavity is incompletely occupied by a greyish, 
rather opaque, but more refractive than when living, granular 
amorphous mass in which neither colour nor chlorophyll grains 
can be distinguished. 
Boussingault * first noticed the phenomena of “ asphyxie " and 
found by means of the gas-analytical method that with Phane- 
rogams in H, CH,, N, or CO, asphyxiation takes place and 
* Boussingault, ‘Agronomie, Chimie Agricole et Physiologie,’ 1868, iv. 
p. 329, 
