A NOTE 
ON 
THE IRRADIATION OF MOTOR IMPULSES. 
By 
N. A. RANDOLPH, M.D., 
PROFESSOR OF HYGIENE IN TIIE UNIVERSITY OF PENNSYLVANIA. 
EXTRACTED FROM THE 
TRANSACTIONS OF THE COLLEGE OF PHYSICIANS OF PHILADELPHIA, 
MARCH 2, 1887 
PHILADELPHIA: 
WM. J. DORNAN, PRINTER. 
1887. A NOTE 
ON 
THE IRRADIATION OF MOTOR IMPULSES. 
By 
N. A. RANDOLPH, M.D., 
PROFESSOR OF HYGIENE IN THE UNIVERSITY OF PENNSYLVANIA. 
EXTRACTED FROM THE 
TRANSACTIONS OF THE COLLEGE OF PHYSICIANS OF PHILADELPHIA, 
MARCH 2, 1887. 
PHILADELPHIA: 
WM. J. D011NAN, PRINTER. 
1887. A NOTE 
ON 
THE IRRADIATION OF MOTOR IMPULSES. 
By 
N. A. RANDOLPH, M.D., 
PROFESSOR OF HYGIENE IN THE UNIVERSITY OF PENNSYLVANIA. 
[Read March 2, 1887.] 
About two years ago this question arose in my 
mind: If a man performs work with the muscles of 
(e. g.) his right hand exclusively, and to the point of 
fatigue, can he thereafter perform as much work, of 
the same nature, with the left hand as he could if the 
right had not been previously exercised? 
It will be seen that this question relates in nowise to 
a comparison of the work of the two hands, but to an 
examination of the work which may be accomplished 
by one hand as conditioned by the previous exercise or 
non-exercise of its fellow of the opposite side. 
It is evident that the answer to this query is depen- 
dent on intracranial processes solely, and that such 
answer would throw some light upon the functional 
independence or interdependence of the two halves of 
the brain. 
In order to answer the question just stated, certain 
conditions are prerequisite. The subject of experiment 4 
RANDOLPH, 
must have no conception of the object of the investiga- 
tion, or he will unconsciously become a partisan of one 
or the other hand. lie must, also, have a very strong 
inducement to exercise his volition to the utmost. 
These conditions were fulfilled in the persons of some 
intelligent and vigorous convicts in the Eastern Peni- 
tentiary in this city. The stimulus was a money prize 
to the man who accomplished the most work in a given 
time. In the prosecution of these experiments I am 
under obligation to the courtesy and assistance of Dr. 
"W. D. Robinson, physician to the penitentiary. 
In the first series of experiments, rubber bulb 
syringes, identical in all their measurements, were used, 
and the amount of water which the men could transfer 
from one vessel to another in a given time was accu- 
rately measured and taken as proportionate to the work 
performed. Some forty observations were made by this 
method, with the uniform result that either hand could 
do more work when its exercise preceded than when it 
succeeded the similar exercise of its fellow of the 
opposite side. It was found, however, that the muscular 
effort could not be entirely restricted to one side of the 
body in this method, as great fatigue was accom- 
panied by a grimacing and writhing which implicated 
the muscles of both sides of the face and trunk. 
A Morse telegraph was next used, the muscular 
movements in this case being restricted to an up-and- 
down motion of one finger of each hand, the number of 
such movements made in a given time being recorded 
on the usual long and narrow strip of paper as dots or 
dashes, in accordance with the celerity of contraction 
and relaxation of the flexors of the finger. The results 
of this series of experiments were uniformly confirma- THE IRRADIATION OF MOTOR IMPULSES. 
5 
tory of those before obtained, but the method had to be 
abandoned as productive of great eye-strain in counting. 
I then had made the instrument which is here shown. 
It consists simply in the clockwork and dial of an ordi- 
nary gas meter, to which a lever is adapted in such 
wise that each flexion of the finger is recorded by an 
appropriate motion of the index on the unit dial. The 
apparatus is fixed in a box, upon which the hand and 
forearm may conveniently rest. The lever projects 
through an aperture in the lid, and a glass plate in the 
side permits the records on the dial to be easily read olf 
and noted. Six healthy prisoners, supplied with the 
incentives of cash and competition, were repeatedly 
examined by this means. To each, fifteen minutes were 
given to make the best record he could with (e. g.) the 
right forefinger, and thereafter the left forefinger was 
similarly exercised for the same time. On the following 
day the same process was repeated, always commencing, 
however, with the finger of the hand which had been 
used second on the previous occasion. ISTo hand was 
ever thus employed twice on the same day. 
The results were practically uniform. The man who 
for fifteen minutes Hexed and relaxed his right fore- 
finger with the greatest speed possible to him would, on 
the following day, accomplish, on an average, nearly ten 
per cent, less work with that finger when its exercise 
was consecutive to a similar exercise of the forefinger 
of the opposite side, than when its work was initial. 
Usually more work could be accomplished by the 
simultaneous exercise of the two forefingers, than by 
their exercise one after the other. In such exercise of 
both hands at once, and apparently from some uncon- 
scious effort at rhythm on the part of the subject, it 6 
RANDOLPH, THE IRRIDIATION OF MOTOR IMPULSES. 
was noted that the movements of the left forefinger 
were generally more active and rapid than when used 
alone, although in both instances the greatest effort at 
speed was evidently made. I am told that some pianists 
have a similar experience, inasmuch as they find it 
possible to exercise the fingers of the left hand more 
rapidly when the right is similarly engaged than when 
the right is inactive. 
The relation of these facts to the observations of Dr. 
S. Weir Mitchell and Dr. Morris Lewis is largely supple- 
mental in its nature. These observers, as is well known, 
showed that the knee-jerk is reinforced by any voluntary 
movement in any part of the body, and that this rein- 
forcement was apparently due to such an irradiation of 
motor impulse from the active centres to other similar 
centres as placed them and their related muscles in a 
condition of heightened responsiveness to external 
stimuli. My studies not only tend to confirm these 
observations, but to show that the fatigue of one centre 
may induce a sympathetic fatigue in other centres. 
These observations are of interest, inasmuch as they 
suggest—that the centres for volition, attention, and 
coordination (or one or more of these) are not, in their 
functional activity, bilaterally symmetrical and inde- 
pendent—that is, that these functions have not attained 
complete differentiation into right and left will, atten- 
tion, or coordination; that, probably, the first effect of 
the voluntary activity of a portion of one cortical motor 
area is a stimulation of the corresponding portion of the 
other hemisphere—a stimulation that may result in its 
slightly premature fatigue; that apparently more work 
can be effected through the voluntary simultaneous 
exercise of two such portions of the motor apparatus 
than by their independent exercise one after the other. DISCUSSION. 
7 
[After the reading of the preceding paper:] 
Dii. S. Weir Mitchell said: The remark that with fatigue 
comes an increasing tendency to convulsive or useless acts of facial 
or other muscles, is interesting. It seems to show that with feeble- 
ness comes increasing waste by overflow of motor energy on to 
distant ganglia. Perhaps in all states of weakness there is more or 
less of this tendency. Admitting the accuracy of Dr. Randolph’s 
facts their explanation is difficult. It may be that the overflow of 
energy on to symmetrically related centres, or on to others, is com- 
petent to weaken them without being strong enough to cause motion; 
and whether this occurs as regards the opposite hemisphere, or only 
as regards opposite spinal centres, is hard to say. 
(As an illustration, we may by a key close the current of two 
batteries, A and B, each competent to set in motion a mechanism. 
Resistances on the one circuit, A, so interfere as to lessen the flow of 
energy below what will move the mechanism. Meanwhile the other 
battery, B, runs to exhaustion. At last we call on battery A for a 
repetition of the full work done by B, and find A unable to effect 
the same work as that done by B, on account of having been par- 
tially disabled by its previous ineffective waste of energy.) 
We are free to speculate as to the relative failure of one hand, 
the last in use, as due to there being but one centre originative of 
will signals to the lower ganglia, and itself capable of fatigue. If, 
however, we entertain any such view, it might be in a measure 
tested by exacting work from a non-symmetrical pair of limbs, as a 
foot and hand. 
I incline toward the use of the overflow theory to explain the 
lowered capacity for work by one hand after exhaustion of the 
other. It would explain why in consentaneous use of two symmet- 
rical parts more work is done than when they follow one the other. 
The overflow would be in this case valuable, and not damaging or 
wasteful. This leads me to relate an experiment which Dr. M. Lewis 
and myself left out of our paper on knee-jerk, but of which I am now 
sure enough to speak. When we use the maximum power of one 
hand on a dynamometer, the coinstantaneous use of the other hand 8 
DISCUSSION. 
adds nothing to the result; and this form of experiment has been com- 
monly used as a test of the reinforcing capacity of the opposite 
member. If, however, using two fingers, or the grip of the thigh 
adductors, on the bulb of a mercural dynamometer until great ex- 
haustion occurs, and we then make a new effort at the moment of 
violent use of another member, the mercury leaps quite to the level 
attained during the first effort by unfatigued muscles. It does not 
seem easy to explain this fact, except by assuming that the overflow 
of energy usually wasted is in this case made efficient. 
The question of muscular, and indeed of ganglionic, tone is brought 
forward in an interesting way by this experiment. When we strike 
the patellar tendon, a sudden, distant, voluntary act adds reinforce- 
ment. What is it that happens to the muscle or ganglion so 
influenced ? Is it made more sensitive to impressions, or with this 
is there a slight flow upon it of motor energy ? And if so, can we 
measure the effect, and thus influence what we conceive of as mus- 
cular tone? 
For some time I have been engaged in discovering if these rein- 
forcements do cause motion—i. e., a slight preparatory muscular 
contraction making the subsequent volition, or other excitatory 
activity, more potent in its results. 
I have been able, so far, to prove that in some spastic cases distant 
muscular effort, such as a grimace, really causes distinct and meas- 
urable movement in the extensors of the thigh and presumably 
elsewhere. This interesting discovery has been confirmed in New 
York and at Harvard. Whether in normal man remote motion is 
thus capable of causing slight shortening of all other muscles does 
not as yet seem clear. In my own experiments I obtained what 
seemed to be the same but slighter results than such as were seen in 
spastic paralysis, and hope very soon to solve doubts, and to be able 
to state my conclusions in more decisive shape. Upon what these 
may be, will depend much of our hope as to realizing clearly the 
true nature of muscular tone. 
We often speak of nerve power as if there were a common stock 
from which are drawn the supplies needed by every active organ, 
and reason that it is unwise to try to carry on at once two functions 
which exact large expenditures—as digestion and intense thought, DISCUSSION. 
9 
or digestion and exercise. Practically the difficulty may be one 
chiefly of blood supply. This is illustrated in the not rare fact that 
some feeble people cannot digest except when at rest. These facts 
suggest the idea that perhaps Dr. Randolph’s cases would lose ten 
per cent, of mechanical capacity after a period of exhausting mental 
labor or during digestion. 
Dr. H. C. Wood said: The old theory which was used to 
explain the principle of counter-irritation, was that there is a certain 
amount of nerve force in the system, and that when by means of 
counter-irritation the nerve force is drawn to a distant point, it is 
removed from the inflamed part. Modern science does not recognize 
the truth of this theory, but it looks to me as though there is a 
certain amount of truth in it. Every one who has worked in a 
gymnasium will recall the fact that he cannot use the two hands 
simultaneously with the same force as he can when the two hands 
are used separately. A man who can put up a fifty pound dumb- 
bell with the right hand and a fifty pound dumb-bell with the left 
hand cannot at one time put up a fifty pound dumb-bell with each 
hand. This shows some relation between the nerve centres which 
we have not as yet gotten at. Dr. Randolph’s contribution is an 
important one looking toward a final solution of this question, but I 
think that it has not gone far enough to enable us to form any 
theories with sufficient grounds on which they may rest to hope that 
the theories are correct. 
I believe that when we use our muscles vigorously, two kinds of 
fatigue are produced. There is a local fatigue and a general fatigue. 
If a man uses the right arm vigorously, he not only fatigues the right 
arm, but also the whole body. I believe that if these investigations 
are continued, it will be found that after prolonged use of the leg, 
there will be loss of power in the arm, perhaps as great as after 
previous use of the other arm. 
Of course, there is a temptation to speculate upon these facts, but 
the matter must be carried further before speculation will amount 
to anything. As suggested by Dr. Mitchell, the relation between 
muscular exertion and mental exercise should be studied. Each one 
knows by personal experience that when mentally fatigued he is 10 
discussion. 
incapable of performing the usual amount of physical labor. This 
is probably independent of any question of overflow, and goes back 
to the higher cerebral centres and their relation. 
Dr. Charles K. Mills said: It seemed to me while listening 
to the reading of this paper that certain well-known clinical facts in 
cases of brain disease have some relation to the subject under con- 
sideration. For instance, an old hemiplegic, if examined carefully, 
will be found to have not only the decided loss of power and accom- 
panying conditions resulting from the lesion on the opposite side of 
the brain, but also a certain diminution of strength in the limbs of 
the other side; a condition which is not entirely due to the general 
loss of physical power present. The phenomena which are exhibited 
by certain spastic cases, or certain cases of unilateral spasm, also 
seem to me to have some relation to this subject. I have carefully 
studied the histories of certain cases of spasmodic infantile hemi- 
plegia. In some of these cases, the autopsy has subsequently shown 
the existence of an irritative, destructive lesion in one hemisphere 
of the brain. If these cases are carefully studied, it will be found 
that in not a few the spasm has first appeared in one limb, or a 
portion of one limb, or in the muscles of one side of the body. 
After the lapse of months or years, the spasms increase and involve 
the whole of the original side, and after a time the other side. 
We have other illustrations of the same idea in cases of dural 
spasm, of which there is at the present time an instance in 
Blockley Hospital, where the spasm was shown by operation to be 
due to irritation of the dura mater. In this case, and in another on 
which trephining was performed, the spasms were at different times 
unilateral and bilateral. Any number of illustrations of this kind 
could be adduced from clinical experience. They show that a lesion 
strictly local, involving only one hemisphere and only a limited por- 
tion of that hemisphere, will give rise to local spasms, and, after a 
time, to general spasms, the other hemisphere never becoming 
involved in any direct pathological process. Radiation of irritation 
from lower centres may, however, explain some of these cases. DISCUSSION. 
11 
Dll. H. Hartsiiorne said: I have given some thought to this inter- 
esting subject, looking at it from rather a different point of view from 
that presented so far to-night. The experiments of Dr. Randolph 
seem to confirm the conclusions of Drs. Mitchell and Lewis quite 
distinctly, but there is, I think, a good deal more than that in them. 
They show that there is not that differentiation of centres which has 
been asserted—that there is not an insulation, as we may say, of the 
centres. I should say there is coordination and unity, more than mere 
sympathy, especially of those of the two sides of the brain and of 
the spinal cord. With regard to the brain, we are all aware that our 
consciousness attests this unity, which is perceptional and volitional. 
Some simple evidence on this point is familiar to us. How is it that 
with the eyes shut we can place any finger of one hand against the 
corresponding finger of the other hand ? This must be done solely 
under central guidance. With reference to Dr. Wood’s illustration, 
it seems to me that the inability to lift two heavy weights at the 
same time is due not to the greater difficulty in the use of the 
muscles, but to the physical inconvenience owing to the structure of 
the body. It is awkward. The experiments of Dr. Randolph cer- 
tainly point the other way. There is another curious experiment 
which I have frequently repeated. If you write on a blackboard 
with both hands at once, I believe that you can write your name 
more readily and certainly backward with the left hand than when 
the left hand is used by itself. You do not need to pay more atten- 
tion to one hand than to the other. Here is an example of bilateral 
unity of volition. 
The first result of Dr. Randolph, I should explain very much as 
is done by Dr. Wood, that is, that there is a certain amount only of 
available dynamic energy at any one time and place, and if that is 
drawn upon, the general sum of dynamic energy, and especially the 
energy in that particular part, is diminished. When one hand has 
done all that it can do the sum of the energy is lessened, and if there 
is a repetition of the work by the other hand the amount is less 
than it would have been if there had not been this consumption of 
power. 
The second result is even more interesting, and, I think, involves 
psychical factors as well as those which are purely physiological. It 12 
DISCUSSION. 
does not seem to me that intracranial processes include all in explain- 
ing these results. The energy belonging to the spinal centres has 
to do with forming the sum total of available energy at the time. 
In explaining the fact that the two hands working together perform 
more work without exhaustion than when they are used one after the 
other, there seem to be two other factors, attention and voluntary in- 
hibition. We all know that fatigue is caused by attention. Dr. 
Randolph spoke of eye-strain, that is also brain-strain. It is said 
that those who in working the submarine cable translate the messages 
by watching the flash of light from a mirror, are only able to work 
one hour at a time. The physical effect of attention is shown by a 
curious experience which has been published in the journals—that 
is, that if a light be placed near enough to the eye to affect the pupil, 
yet allowing the subject to see beyond, it was repeatedly observed 
that if the attention was directed to the light the contraction of the 
pupil was decidedly greater than when the attention was directed 
to something beyond. There are also some curious results reported 
not long ago by llaggi. In experimenting with faint sounds, such 
as the ticking of a watch in a room where all was silent, he found 
that there were intervals when no sound was heard. These periods 
were as long as from seven to twenty-two seconds. The period 
during which there was audition was from seven to fifteen seconds. 
Taking the view" which I have already expressed in regard to 
the unity or coordination of the cerebral and spinal centres of the 
whole cerebro-spinal axis, it may be that the natural and spontaneous 
method of volition is for the impulse to descend and distribute itself 
symmetrically to the two sides, and that attention is necessary to 
prevent this and to make its direction oblique and concentrate it 
upon one side, and as a result of this effort of attention fatigue is 
induced. 
I am not a believer in the normal functional inhibition of nerves, 
although this view is held by most authorities. It is apparent that 
we have three kinds of inhibition: one of the lower centres by the 
higher, the spinal axis by the brain; another form is pathological, 
of which there are many instances; and the third form is voluntary 
inhibition. I need say nothing more in the way of illustration 
than to refer to the great fatigue or strain which is induced by the DISCUSSION. 
13 
effort to restrain strong emotions. There are some circumstances in 
which it is the hardest thing possible to keep still. That is what 
I mean by voluntary inhibition. If it be true, as I have conjectured, 
that there is this normal symmetrical mode of volitional action from 
the brain downward through the spinal cord to the two sides rather 
than to one side, there is need to restrain the one not allowed to act. 
This effort to restrain one side is a draft upon the cerebro-spinal 
energy and this involves some fatigue, and thus there is less power 
if one act follows the other than if both acts are performed at the 
same time. 
It seems to me that the greatest importance of such observations 
consists in their effect in modifying the idea which was formerly held 
as to the meaning of the term “nerve centre." Long ago, Flourens 
suggested that there is an equivalence of function for all parts of the 
brain. This view, of course, cannot be held. Later, Brown-Sequard 
formulated the idea that one hemisphere might do all that the whole 
brain could do, not in power and endurance, but in function. There 
has been published within a year a work by Luciani and Seppili 
on cerebral localization, in which they very clearly point out that a 
centre is not a point or a cell, or a collection of a few cells; but the 
idea might be illustrated by our use of the terms “centre of busi- 
ness,” or “ centre of fashionable residences while the business may 
be conducted largely in one locality, still it is not confined to that 
part. In one of the diagrams of the authors mentioned, the visual 
centre is shown by a dark place, the central portion of which is the 
darkest. This view explains many experiments where the destruc- 
tion of what is called a centre does not prevent the performance 
of the function belonging to that centre. It seems to me to be an 
important advance in nerve-physiology to get rid of the idea of the 
insulation of centres. 
Such experiments as those of Dr. Randolph are of great interest 
in connection with pure physiology, and also in connection with 
psycho-physiology, which has now almost displaced the old psy- 
chology in the schools, and which occupies a large part of the atten- 
tion not only of physiologists, but also of psychologists. 14 
DISCUSSION. 
Dr. Francis X. Dercum said: The thoughts that suggest 
themselves to me have, in a large part, been embodied in what Dr. 
Wood has said, and in the latter part of the remarks of Dr. Harts- 
horne. I think it extremely probable, and ha/ve so expressed myself 
in a paper read before the American Neurological Society, that the 
nerve centres are not centres defined with anatomical and mathematical 
precision. The centre is simply the point of greatest functional 
activity. Take, for instance, the centres for motion, and the sensory 
areas in the cortex ; these are nothing more than the pointss where the 
various motions and sensations are focussed. These points are, to me, 
nothing more than the gateways of ingress and egress to the general 
cortex. It also seems to me that the nervous system being a whole, 
if any one part acts it must necessarily tire the whole. If one part 
acts, all the other parts must be fatigued; and the evidence is all the 
time increasing that the interdependence is so great and intimate that 
this can be held not simply as a mere speculation, but can be regarded 
as a fact. To such conclusions does the work of Dr. Randolph, and 
also that of Dr. Mitchell and Dr. Lewis, incline.