386 
MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
oxygen ceases to be pereeptible, the latter being overpowered 
by the increased respiration before assimilation actually ceases. 
Thus Kreusler * found that assimilation begins to decrease at 
80? C., at 45° C. is not entirely stopped, and at 50° C. is imper- 
ceptible (Rubus and Ricinus). The stoppage of assimilation is 
here a direct effect of the temperature to which the plants are 
exposed. To produce a stoppage of assimilation as an after-effect 
of the exposure, and persisting after the exposure has ceased, is 
by no means easy. If the exposure is severe the plant may be 
fatally injured and not recover at all; if less severe, it may be 
either unaffected or recover almost immediately. This is shown 
in Table F. The plants were exposed for 1 day at the tempera- 
ture given, and after examination at the same temperature, 
brought to a temperature of 18° C. and kept under continuous 
No 
observation. 
TABLE F. 
At 31° O. to 32° C. At 36° O. to 37° C. 
Chara fragilis, ........ Rotate" rapid. Evol" of O very| Rotatn slightly slowed. 
weak, in y h. at 18? C. mod.|  evolyof O. In jh. at 18°C. 
active, in 4 h. quite active.| weak, in 4 h. mod., and in 1h. 
Rotat” slightly slower. quite active and rotat" normal. 
Elodea canadensis ...... Very weak evol” of O. Few | Noevol® of O or rotat”. 
Selaginella helvetica. 
Oxalis Acetosella. 
Cystopteris fragilis. 
Metzgeria furcata, 
Orthotrichum affine. 
Parmelia parietina. 
Dicranum scoparium. 
Bryum cespititium ... 
| 
cells slow rotat? 3 h. at 18? C., 
rotat? active, evol® of O mod. 
active, and in 4h. quite active. 
Very weak evol” of O, in 4 h. to 
3 h. at 18? C. mod. active, and 
in 1 h. quite active. 
Weak evol” of O, fairly active 
in 4 h. at 18? C., quite in 4 h. 
Rather weak evol" of O, quite 
active in 4 h. at 18? C. 
In fh. 
at 189 C. rotat®, active, no 
evoln. of O, but in h. weak 
and in 1-2 hrs. active. 
No evol” of O, in 1 h. weak, in 
4h. mod. active, and in 1-2 
hrs. quite active. 
No evol” of O, weak in š h., 
mod. active in 1 h., and quite 
in 2 hrs. 
No evol” of O, weak in 4 h. at 
18° C., mod. active in 4 h. 
quite in 1 h. 
Table G shows that plants kept at 37° C. to 38° C. for 3 days, 
if kept moist and well supplied with oxygen, are all living, and 
almost no inhibitory after-effect upon assimilation has been 
produced. 
* Kreusler, * Beobachtungen über die Kohlensiure-Aufnahme und -Ausgabe 
der Pflanzen,” in Landw. Jahrb. 1887, Bd. xvi. pp. 711-715. 
