IN VEGETABLE BIOLOGY. 225 
simple apostrophe ; but I am not in a position at present to give 
figures in elucidation of this point. 
To proceed now with the phototactic theory of photolysis. It 
is known that protoplasm has a wonderful power of slowly adapt- 
ing itself to the conditions under which it is placed. If, there- 
fore, the movements, in virtue of which chlorophyll is epi- and 
apostrophized be protoplasmic alone, and without any arriere 
pensée, as it were, to chlorophyll itself, we should expect to find 
that the protoplasm of aquatic types would be toned to light of 
low intensity, because it is only under unusual conditions that 
these plants are exposed to highly-diffused illumination or direct 
sunlight. Upon the same grounds it might be anticipated that 
sun-loving types would have their grains in epistrophe in light 
of intensity sufficient to induce apostrophe in aquatics ; in other 
words, the position of its epistrophic interval ought to depend 
upon a plant’s habitat, so far as this is affected by illumination ; 
and this it has already been shown is the case. 
Secondly. The view that protoplasm is toned to a certain in- 
tensity of light is warranted by the fact that apostrophe of the 
grains in cells neighbouring on dead cells is more readily effected 
with light of good enough quality to cause apostrophe in healthy 
cells than it is in these latter, and can take place at grades of 
illumination insufficient to apostrophize the grains of healthy 
cells. Upon Bóhm's theory, proximity to a dead cell must in- 
crease the sensitiveness of chorophyll to light ; while supporters 
of Stahl would be forced to admit that the neighbourhood of dead 
cells is a region where assimilation is more active than ordinary. 
It is submitted that this alone drives Bóhm's and Stahl's theories 
from the field, whereas the supposition that a dead or dying cell 
must exert a lowering influence upon the protoplasm of ita 
neighbours, not only because its own protoplasm is in a morbid 
condition, but because all the protoplasts are placed in continuity*, 
is surely by no means an extravagant one. One might therefore, 
upon these grounds, predict that the epistrophie interval of the 
cells in question would not reach so far to the right as does that 
of healthy cells, : . 
Thirdly. If the tone of the protoplasm with respect to light 
depends on its quality, it ought to be expected that the epistro- 
phic interval of cells, the protoplasm of which is injured by any 
cause whatever, would be curtailed towards the right. Frauk 
* I have obtained fair verification of this statement, 
