Dept.] 
NATURAL SCIENCES OF PHILADELPHIA. 
7 
matic. This was tlie view taken by Dr. Leidy of the results observed by him 
in analogous experiments made several years since, npon frogs, flies, &c. He 
believed that the conveyance of impressions, in insects, for instance, to the 
chain of ventral ganglia, should be expected, without supposing perception to 
produce the apparently voluntary movements. While experimenting at one 
time upon pigeons. Dr. Leidy kept one alive, after the removal of the cere- 
brum, for nearly two months. It spent much of the day in walking up and 
down the room, but never passed through the open door into the room adjoin- 
ing, the dark shade of which appeared to have the eflfect, through the retina, of 
a bar or obstacle. All its motions seemed, to Dr. Leidy, to be automatic and 
unreasoning ; approaching the fire, for example, for warmth, but getting so 
near as to burn itself, having, repeatedly, to be picked out of the ash-pan. 
Acts are often set down as evincing consciousness, which are really automatic, 
such as the darting of a frog at a bright object, or of a fly against a window- 
pane. The same act will be repeated a thousand times in the same way, with- 
out learning by the experiment, it being the mere result of an impression on 
the organs of sense. 
Mr. W. Parker Foulke suggested an enquiry, in regard to the somewhat 
complex and determinate movements of newly-born animals, which could not 
possibly have learned by experience how to perform such acts ; if these were 
automatic, how do they differ from those described in the paper of Dr. Paton ? 
Moreover, in using the term ' ' perceptive act, ' ' does Dr. Paton mean that the 
animal is believed to be conscious of the impression through the spinal cord, 
and to act voluntarily ? 
Dr. Richardson considered that this was his meaning, and urged, that in 
some of the experiments related in the paper, sensibility appeared to be shown 
by the purposive character of the movements made. Thus, when an animal, whose 
brain has been removed, is lightly touched about the neck, and makes a 
special movement to brush off" the irritant, this motion is only one of many 
movements possible to the same muscles, and one of the least frequent or nsitii- 
ral to them. We must, therefore, infer sensibility to account for this deter- 
minate movement, instead of the more simple and uniform contraction, such 
as reflex action produces. 
Dr. H. Hartshorne believed that diff"erent modes or degrees of irritation of 
the same surface might produce variable contractions of muscles, under reflex 
action alone. 
Dr. Leidy confirmed this opinion, by examples, in the- movements of frogs, 
flies, &c, from which the brain had been removed. 
Dr. Richardson : — Do not these examples really show the possession of sensi- 
bility by the cord or ventral ganglia, for which the author of the paper con- 
tends ? 
Dr. H. Hartshorne considered that the statement of the paper, that reflex 
actions are always uniform under impressions upon the same part, is true only 
when the impressions are like in degree, and are conveyed by the same nerve- 
fibres, to the same central ganglia. Thus, the impression of light upon the 
retina, which, by one reflex circuit causes the contraction of the pupil, will, by 
another, induce a more general movement of muscles, or the act of sneezing, or 
the flow of tears. Moreover, a purposive or determinate character in move- 
ments does not remove them from the category of automatic actions. Thus, for 
instance, those called instinctive in lower animals, and others, in the higher, 
designated as sensori-motor by some physiologists, are still reflex, that is, de- 
pendent on an impression from without, acting through a complex nervous ap- 
paratus. Dr. Hartshorne has not, in fact, seen satisfactory evidence of the 
existence of will in any animal except man, — the actions of all the others being 
explicable upon the idea of more or less complex automatism ; and, where the 
subject is so obscure, it is most philosophical to assume only the one idea or 
supposition, which will account for the facts, rather than two, as we must do 
1858.] 
