rately the conditions which
modify the rate of growth. Experiments which would have taken months and
their results vitiated by unknown changes, can now be carried out in a
few minutes.

Returning to pure science, no phenomena in plant life are so extremely
varied or have yet been more incapable of generalisation than the
"tropic" movements, such as the twining of tendrils, the heliotropic
movements of some towards and of others away from light, and the
opposite geotropic movements of the root and shoot, in the direction of
gravitation or away from it. My latest investigations recently
communicated to the Royal Society have established a single fundamental
reaction which underlies all these effects so extremely diverse.

Finally, I may say a word of that other new and unexpected chapter which
is opening out from my demonstration of nervous impulse in plants. The
speed with which the nervous impulse courses through the plant has been
determined; its nervous excitability and the variation of that
excitability have likewise been measured. The nervous impulse in plant
and in man is found exalted or inhibited under identical conditions. We
may even follow this parallelism in what may seem extreme cases. A plant
carefully protected under glass from outside shocks, looks sleek and
flourishing; but its higher nervous function is then found to be
atrophied. But when a succession of blows is rained on this effect and
bloated specimen, the shocks themselves create nervous channels and
arouse anew the deteriorated nature. And is it not shocks of adversity,
and not cotton-wool protection, that evolve true manhood?

A question long perplexing physiologists and psychologists alike is that
concerned with the great mystery that underlies memory. But now through
certain experiments I have carried out, it is possible to trace "memory
impressions" backwards even in inorganic matter, such latent impressions
being capable of subsequent revival. Again the tone of our sensation is
determined by the intensity of nervous excitation that reaches the
central perceiving organ. It would theoretically be possible to change
the tone or quality of our sensation, if means could be discovered by
which the nervous impulse would become modified during transit.
Investigation on nervous impulse in plants has led to the discovery of
a controlling method, which was found equally effective in regard to the
nervous impulse in animal.

Thus the lines of physic