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posterior side. We will now ascertain under what conditions this 
will be the case. 
As has been pointed out the direct result of the illumination is 
a decrease of sensibility, which is the greater according as the 
intensity of the illumination is stronger. It follows that under the 
influence of this factor the sensibility of the posterior side can never 
fall below that of the anterior side. 
It has also been pointed out, however, that after some time the 
sensibility increases again at first slowly, then quicker and quicker, 
until after some time a velocity of increase is reached in agreement 
with the magnitude of the then existing sensibility. We should have 
to know now when the increase of the sensibility begins, and how 
long it lasts before it has reached its proper rate. This, however, 
has been investigated omly in a single case. Meanwhile we are 
probably justified in supposing that these initial stages will be gone 
through the quicker according as the decrease of the sensibility has 
been greater. If this supposition is correct, then the increase of the 
sensibility in the anterior side must commence before that in the 
posterior side, at least when the sensibility in the latter is not wholly 
destroyed. If, therefore, the illumination is discontinued at a moment - 
when the rate at which the sensibility increases has not yet reached 
its highest value in the posterior side, then the sensibility in the 
anterior side, if not too much below that in the posterior side, must 
soon prevail. This condition will then persist until the sensibility in 
both sides has reached once more its original value. If this view is 
right, the antiphototropic curvature can never be followed by a 
second normal curvature. In my own experiments, I may state such 
a second normal curvature could never be detected. 
With highly intense light the antiphototropie curvature is not preceded 
by a normal one. If in this case the sensibility at the close of the 
illumination is still greater in the posterior side than in the anterior 
side, this difference does not persist long enough to express itself in 
a curvature of appreciable magnitude. Such antiphototropic curvatures 
are seen in the figures 11 and 12 of my paper cited above, which 
show the effects of an illumination respectively with 50 M.C. and 
with 250 M.C. They are most conspicuous with an exposition time 
respectively of 3'/, minutes and 40 seconds. 
With a less intense light, on the other hand, the antiphototropic 
curvature is preceded by a normal one. The sensibility of the posterior 
side remains in this case long enough above that in the anterior 
side to express itself in a curvature. 
Of course this curvature will be stronger according as the light 
