1885.] Fsychology. — 1125 
greatest sensibility. Probably all hairs are tactile organs, On 
the dorsal side of the left hand the minimal stimulus for a circu- 
lar group of pressure points was represented by the figure 0.2 3, 
while* on certain intermediate points the force necessary to be 
applied in order to evoke sensation was represented by 1.5. The 
pressure points on the back of the hand were more sensitive than 
those upon the middle of the fore-arm and still more so than 
those upon the thigh. The skin appears most sensitive to pres- 
sure where the tactile corpuscles of Krause are most numerous. 
In true scar tissue neither cold, warm nor pressure points can be 
discovered. Many points of the skin are insensitive to pain, as 
tested by needle-puncture, while others are extremely susceptible. 
It is very probable that sensations of pain depend upon direct 
injury of a sensory nerve trunk.—Zeitschr. f. Biologie, Bd. xxi, p. 
145. 
PSYCHOLOGY. 
Minp anD Morion.—The Rede lecture delivered last week in , 
the Senate House, at Cambridge, by Mr. G. J. Romanes, M.A., 
F.R.S., was entitled “ Mind and Motion.” After giving some ac- 
count of the teaching of Hobbes, who laid it down, on the one 
hand, that all our knowledge of the external world is but a 
knowledge of motion, and, on the other, that all our acquisitions 
of knowledge and other acts of mind imply some kind of “ 
tion, agitation, or alteration, which worketh in the brain,” Mr. 
-Romanes pointed out, as regards the internal world, that physi- 
ology has proved that molecular movements of nervous matter 
are concerned in all the processes of reflex action, sensation, per- 
ception, instinct, emotion, thought, and volition. The lecturer 
detailed the discoveries which of late years have been made by 
physiology concerning the rate at which these movements travel 
ong nerves, the period of molecular vibrations in nerve centers, 
the time required for processes of thought, and the quantitative 
relations between brain-action and mind-action. When physi- 
ological instruments fail to take cognizance of these relations, we 
gain much additional insight touching the movements of nervous 
matter by attending to the thoughts and feelings of our own 
minds, for these are so many indices of what is going on in our 
b: 
rains. Proceeding to contemplate the mind, considered thus as 
a physiological instrument of the greatest delicacy, he argued 
that the association of ideas is but an obverse expression of the 
fact that when once a wave of molecular disturbance passes 
through any line of nerve structure, it leaves behind it a change 
in the structure, such that it is afterwards more easy for a similar 
-wave when started from the same point to pursue the same 
course. Such being the intimate relation between brain-action 
and mind-action, it has become the scientifically orthodox teach- 
ing that the two stand to one another in the relation of cause to 
