OcToBER 5, 1899] 
venient term, was spoken of by Dr. Anderson and myself as a 
reflex action. It is perhaps better to call it a pseudo-reflex 
action. 
Regarded from the customary point of view, a pseudo-reflex 
differs widely from a reflex action. The one is brought about 
by stimulating an efferent or motor fibre, and the other by 
stimulating an afferent or sensory fibre. 
But suppose we compare them from another point of view. 
Fig. 2 is a diagrammatic representation of a pseudo-reflex. A 
nervous impulse passes up one branch a of a cell A, passes to 
another branch a’, so excites a cell B and its nerve-fibre 8. 
Fig. 4 is a diagrammatic representation of a simple true 
reflex in the voluntary muscle. A nervous impulse passes up 
one branch a@ of a cell A, passes to another branch a’, so 
excites a cell B and its nerve-fibre B. 
You see the two can be described in exactly the same terms, 
and both are reducible to the diagram of Fig 3. It is true that 
the cells A and B are not similarly situated in the two cases ; in 
the pseudo-reflex A is in the spinal cord, and B is outside it in 
a peripheral ganglion ; whereas in the true reflex A is outside 
the spinal cord, in a spinal ganglion, and B is inside the cord. 
But then no one has even suggested that the position of a nerve- 
cell determines whether an action in which it takes part is a 
reflexor no. So that this point is irrelevant. And so it might 
be urged that the one action has as good a title to be called 
a reflex as the other. I do not, however, wish to insist too 
much on this comparison. I am inclined to say, after Touch- 
stone, ‘* An ill-favoured thing, sir, but mine own.” 
If, as some think is the case, the spinal ganglion cell re- 
ceives the nerve-impulse conveyed by the peripheral nerve 
process, and modifies it before passing it on to the central 
process, this establishes a distinguishing character for the true 
reflex. It would be probably an axon plus dendron reflex, 
the pseudo-reflex being simply an axon reflex. The important 
known functional difference between the reflex and the 
pseudo-reflex is that in the former case the nerve-endings of 
the primarily affected nerve-fibre are specially differentiated 
for receiving nerve-impulses, and in the latter case these end- 
ings are specially differentiated for imparting nerve-impulses. 
And, on the whole, it is probable that the pseudo-reflex is 
not a normal part of the working of the body, but comes 
into play only as it were by accident. I do not, however, 
regard this as quite certain. 
The pseudo-reflex I have spoken of is caused by the ex- 
citation of nerve-fibres before they reach the ganglia—z.e. of 
pre-ganglionic fibres. But the fibres which are given off by 
the ganglia also branch, so that it appears inevitable that we 
should have in certain circumstances an action related to a 
reflex caused by a stimulation set up in one of these branches 
spreading to the rest—z.e. a spreading out of impulses in post- 
ganglionic fibres similar to that which occurs in pre-ganglionic 
fibres. Turning to the diagram, Fig. 1, a nervous impulse set 
up in one branch—possibly by a contraction of muscle-cells to 
which it runs—would spread to other branches and cause con- 
traction of the muscle-cells in connection with them. You will 
notice that this spreading out of impulses does not necessarily 
involve the stimulation of any nerve-cell ; it might perhaps be 
distinguished as zyradzatzon. It would, probably, be very 
local in action, unless there were overlapping of the districts 
supplied by the several nerve-cells, in which case a not incon- 
siderable spreading out of a local contraction might take place, 
giving rise to a peristaltic wave. 
It must be pointed out that it has been assumed that in the 
sympathetic nervous system an impulse cannot pass from a 
motor fibre through the nerve-cell from which the fibre arises 
and affect any other nerve-fibre or nerve-cell. There is good 
ground for this assumption, but the experimental evidence 
might certainly be more complete. 
To return to our main line of argument, we have good evi- 
dence that nervous impulses set up in one spot may affect 
regions more or less remote by a mechanism which does not 
involve the presence in the sympathetic system of special sensory 
nerve-cells with peripheral sensory nerve-endings. And so far 
as investigation has gone at present, I think that all the ap- 
parent reflex actions can be explained without reference to such 
sensory apparatus. And so I take the analogy of the peripheral 
ganglia with the central nervous system to be misleading, and 
consider that all the nerve-cells of which we have been speak- 
ing are motor nerve-cells, and that they all conform to the 
simple plan shown in Fig. 1. Thus the whole consists of a 
NO. 1562, VOL. 60] 
NATURE 
561 
duplication of one type; a cell in the spinal cord which 
branches, each branch ending ina single cell ; each of these 
cells sends off a nerve-fibre which branches, the branches ending 
in a group of involuntary muscle or gland cells. 
That I regard as the real working mechanism, but there are 
two reservations to make. All the tissues of the body may be 
looked upon as engaged in a lifelong process of carrying out 
experiments, and I am prepared to believe that there are in 
the body what may be spoken of as the residues of these 
natural physiological experiments, either the beginnings of ex- 
periments which have not succeeded, or the melancholy ends 
of those which once partially successful have failed later. Such 
possibly may be the nerve-cells which have been described in 
sympathetic ganglia as sending their nerve-fibres to other 
nerve-cells. 
Secondly, in this account I have not included the nerve-cells 
which exist in the wall of the alimentary canal, and the cells 
of Auerbach’s and Meissner’s plexuses. These ‘‘ enteric” 
nerve-cells belong, I hold, to a system different from that of 
the other peripheral nerve-cells. With regard to their con- 
nections I do not think anything can be said with certainty. 
Regeneratzon. Specific Nerve Energy.—One other problem 
presented by this involuntary system we may say a few words 
about. You know that when a nerve in the hand or arm is 
cut the nerve will in proper conditions grow again ; and the 
lost feeling and the lost power over the muscles will return. 
The recovery is brought about by the part of the nerve which is 
attached to the spinal cord growing along its old track and 
spreading out as before in the muscle, skin and other tissue. 
At any rate, that is the method for which there is most evi- 
dence. You may know also that when the nerve-fibres in the 
spinal cord are similarly injured, they do not recover function. 
Regeneration in the latter case implies that the nerve-fibres 
have to form fresh endings in connection with nerve-cells. If 
this were more difficult than the formation of nerve-endings in 
muscle and other non-nervous tissues, the difference which 
exists as regards recovery of function between the nerve-fibres 
of the limb and nerve-fibres of the spinal cord would be 
readily explainable. But recent experiments show that the 
nerve-fibres which run from the spinal cord to the peripheral 
ganglia—?.e. pre-ganglionic fibres—re-form with ease their con- 
nection with nerve-cells, so that we may probably seek in 
mechanical conditions for the reason of the absence of re- 
generation of the fibres in the spinal cord. Possibly some way 
may be found of improving the mechanical conditions, and so- 
obtaining regeneration. That question, however, we need not 
enter into. 
The regeneration of the pre-ganglionic nerves presents some 
very remarkable features. The nerve-fibres which end in a 
sympathetic ganglion are rarely, if ever, all of one kind—that 
is to say, they do not all produce the same effects. Thus, of 
those which run to the ganglion in the upper part of the neck, 
some cause the eyelids to move apart, some cause the pupil to 
dilate, some cause the face to become pale, some cause the 
glands of the mouth or skin to secrete, and others have other 
effects. These different kinds of nerve-fibres run, in large part 
at any rate, to different nerve-cells in the ganglion. Thereare 
in the ganglion several thousands of nerve-cells closely packed 
together. And it would seem hopeless for each kind of 
nerve-fibre as it grows again into the ganglion during regener- 
ation to find its proper kind of nerve-cell. Nevertheless, nearly 
all of them succeed in doing this. The nerve-fibres which 
normally cause separation of the eyelids, or dilatation of the- 
pupil, or pallor of the face, or secretion from the glands, pro- 
duce the same effects after several inches of their peripheral. 
ends have formed anew. 
The fact offers at first sight a striking proof of a specific 
difference between the different classes of nerve-fibres and 
different classes of nerve-cells. Through the matted mass 
formed by the delicate interlacing arms of the nerve-cells, the 
ingrowing fibres pursue their tortuous course, passing between 
and about hundreds of near relations until they find their im- 
mediate stock, whom they clasp with a spray of greeting 
tendrils and so come to rest. 
Absolute laws seem unfitted for a workaday world. For 
closer observation shows that the fibres have not always this 
marked preference for their ownstock. The nerve-fibres of the 
cervical sympathetic, the nerve I have spoken of above, do not 
often go astray, at any rate so far as is known. But they do 
sometimes ; thus it may happen that some nerve-fibres which 
