396 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
internodal medullary cells of Chara. In other cases, it is com- 
paratively easy by exposure to cold to cause a stoppage of 
rotation. There does not seem to be any inherent essential 
connection between the recovery of rotation and the recovery of 
assimilation—the one may be active whilst the other is still weak 
or absent. 
Experiments with more resistant land plants show that within 
certain limits a short exposure to a very low temperature pro- 
duces the same result as a longer exposure to a higher tempe- 
rature. 
Taste L. 
Plants for 3 weeks at average temperature of —2° C. to —3? C. 
Examined at 1? C. All remained living. 
Ceratodon purpureum ; Weak evol? of Oxygen, which after 1 h. at 
Oxalis Acetosella. 15? C. is active. 
Bryum cespititium ; No evol? of O; commences in 1 h. at 15? C. 
Sphagnum acutifolium. and is in 1 h. active. 
Selaginella helvetica ; No evol” of O; in 1 h. at 15? C. fairly active 
Marchantia polymorpha ; and in 3 h. quite active. 
Lunularia rediviva. 
TABLE M. 
, Plants for 15 hours at a temperature falling from —2° C. to —9? C. 
| Examined at 1° C. 
Brassica Napus. Seedlings. Assim. faint or imperceptible ; in 3 h. 
| at 15° C. active. 
Hedera Helix; Cu- | No evol? of Oxygen, but in 3 h. at 159 C. assim. 
pressus sempervirens. is quite active. 
| Buxus sempervirens; | No evol” of Oxygen. In 3 h. weak and in 1 day 
| Thuja orientalis. fairly active assim. A few leaf-cells in Buxus 
| die and do not recover. 
The same 5 plante exposed for 6 h. to a temperature falling from 0° C. to 
—8? C. showed when examined at 1? C. a weak but distinct power of 
assimilation, which after 1-2 h. at 15? C. became active. 
A series of experiments performed with plants from the 
temperate, cold, and tropical houses showed as regards the 
function of assimilation very different powers of resistance to 
exist between these three classes of plants. In Table N the 
leafy branches of cool temperate plants were exposed under 
