412 MR. A. J. EWART ON ASSIMILATORY INHIBITION. 
than other water-plants are. The chalky incrustation on Chara 
is certainly most important as a protection against the injurious 
action of even minute traces of fixed acid. 
In plants of Chara fragilis after 16 hours’ immersion in 0°0005 
per cent. H,PO, all end cells and most cortical cells are dead, no 
evolution of oxygen is shown, and none after 2 hours in water. 
In 4 hours a weak evolution of oxygen in parts and in some cells 
rotation can be seen. Next day all living parts show moderately 
active assimilation. In a few cases the cortical cells are killed 
and become white, blanched, and transparent, whilst the medul- 
lary cell, now rendered plainly visible, shows active rotation and 
assimilation. 
The following tables give the results of experiments with 
water-plants and mosses, the plants being completely immersed 
in solutions of varying strengths for many hours and then 
examined after washing to remove all traces of adhering acid. 
TABLE V. 
Elodea canadensis. Utricularia vulgaris. 
After At first no rotation, but in a | Most branches weak evola of 
_ 24 hours few minutes it commences| O, active in few, and in few 
in 0°01 p.c. | and is in 4-4 hour active. | none. In 4 h. weak evol? 
H;PO,. Most leaves no assim., but | of O in all cases, in many 
weak evol” of O in many, and | branches active, and in 1 to 
in 3 h. weak evol» of O in| 2h. about normal assim. in 
nearly all cases, in 1 h. in all| all cases. 
cases and active in some. In 
2-3 h. assim. is about normal. 
After Central leaves of apical tufts | Younger branches living, but 
_ 24 hours and basal cells of most leaves | no evol” of O. In 2h. weak 
in 002 p.c. | living, but no evol" of O.| evol” of O in some branches 
H,PO,. After 4h. weak in many cases, | and in 4 h.in most. In8h. 
after 8 h. in all cases, and | assim. is moderately active, 
in 1 day active evol” of O| but in few branches still 
from all living cells. weak or absent. In 1 day 
active assim. in all cases. 
After Leaves of apical tuft more | Youngadult branches partially 
, 24 hours or less cells living, but no | or entirely living. No evol” 
in 0-04 p.c. | evol" of O, none after 2h.,| of O and none after 2 b. 
H;PO,. weak in few cases in 4 h.; in| Weak in 4h. from most living 
8 h. weak assim. in most liv- | branches, in 8 h. in few cases 
ing cells, which in lday is| mod. active, but in some 
moderately active. still none. In 1 day all 
living branches show from 
weak to mod. active assim. 
