Medical Officers of the Army of India.
heat to axes, the application in some cases being carried out by means of flame,
in others by contact of heated metallic surfaces, and, in still others, by means
of focussing the sun's rays on the surface with the aid of a lens. The general
results were not in any case alike. There was always a more or less extensive
propagation of movement along the course of the axis, but while in all cases
centrifugal propagation manifested itself and, as a rule, was extensive, in only
18 cases was there any centripetal action, and in these of very limited extension
only.
Table XI deals with the effects of section of the tips of axes in 38 cases
in which the phenomenon of propagation of action manifested itself in va-
rious degrees of intensity, the extension being sometimes very limited, at others
very widely diffused. In dealing with this table it must be pointed out that
phenomena of propagation of movement are by no means necessarily present in
every case of such distal sections. They do not by any means occur with the
same constancy with which those following heating of axes occur. The table,
therefore, is to be taken simply as illustrative of effects frequently following
distal section, and not as illustrating an invariable phenomenon.
In proceeding to consider the bearing of the data in the first of these tables
on the question of the causation of propagation of movement, the most striking
phenomenon presenting itself to observation is that of the rarity and limitation
of centripetal as compared with centrifugal propagation. In only 18 cases was
there any centripetal propagation, and in 15 of these the action was limited
to a single leaf, while in the remaining 3 cases it did not extend beyond two
leaves. In the same cases centrifugal propagation manifested itself along the
entire course of the axis beyond the point of application in 13 cases, and in the
remaining 5 the amount of centrifugal extension exceeded that of centripetal
action. In the remaining 50 cases in which centrifugal propagation alone
manifested itself, movements took place in all the leaves along the axis beyond
the site of application in 30 cases, and in the remaining 20 cases the propa-
gation was, as a rule, relatively extensive, being only in 3 instances limited to a
single leaf, and in the others manifesting itself in from 2 to as many as 14 leaves.
Now, how far are these phenomena explicable by the theory of propagation
as the result of conduction of impulses along continuous masses of protoplasm ?
If they are to be explained by it, it is necessary to assume that the protoplasm
has a greater conductive power centrifugally than centripetally, for it can only
be as the result of this that propagation occurs so much more frequently and ex-
tensively in the centrifugal than in the centripetal direction. This difference in
conductivity must, moreover, be very great to account for the great general
differences in the degree of extension and for the frequency with which centri-
fugal action alone manifests itself, even where the site of application is very
close to an inferior leaf and relatively remote from any superior one. But there
is, so far as I am aware, absolutely no independent evidence in favour of any
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