REPORT BY SURGEON-CAPTAIN J. F. EVANS.
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(a) Symptoms of distress.—Symptoms
of distress or discomfort, as evinced by constant or
peculiar cries usually preceded the development of the symptoms of the other types, the animal
later on either displaying disturbance of the sensory-motor mechanism or falling gradually asleep.
Symptoms of distress were in some instances the only effect induced. But such conditions
are obviously so liable to misinterpretation, that to class them as definite physiological effects
would be hardly admissible. Accordingly, where a condition to be described as one of distress
was the sole effect, the dose administered is recorded as having failed to produce definite symp-
toms. As already stated, however, such symptoms, varying in the degree of their manifes-
tation, almost invariably preceded those of the other types. It is difficult to describe the
vocal sounds that may be emitted by a distressed cat, but one cry was occasionally heard
from animals in this condition, which deserves a passing notice. It may be described as a high-
pitched, prolonged wailing cry, and was particularly objected to by the laboratory staff, who
informed me that the cry was unusual-and considered a sign of ill-luck in Bengali households.
(b) Disturbance
of the sensory-motor
apparatus.—Disturbance
of the sensory-motor
apparatus was manifested by the occurrence of unusual movements on the part of the animal,
or by some apparent difficulty in maintaining its equilibrium on standing, or by the partial
loss of motor power. The reference of all these manifestations to some effect produced by
the drug on the sensory-motor apparatus may be objected to as arbitrary, especially as in the
case of animals it is not possible to put the matter to the test in the same way as in man.
But as the most important of the symptoms to be described under the above heading indicate
interference with those muscular actions which go on for the most part independently of the
will or reflexly, and as the other symptoms may be explained on the same hypothesis, though
possibly incorrectly, it seems permissible to class these manifestations altogether.
Rocking movements.—It will be seen that the drug in minimum or larger doses constantly
induced at some period of its action a peculiar and unusual rocking movement of the body upon
its supports. These movements were very constant, not only in their character, but also in
their occurrence. Their occurrence to a marked extent came to be regarded as the least admis-
sible evidence of definite physiological effect. Coming on at a period subsequent to the
administration of the drug, which varied with the amount of the dose and lasting a variable
period, they were usually followed by either more marked sensory-motor disturbance or by
sleep. Occasionally, though not usually, the production of these movements was almost
the only effect induced by certain doses of the drug. The movements were apparently quite
involuntary, and were best displayed when the animal was in the sitting or standing posture,
disappearing when it lay down. They consist in a rhythmical side-to-side or backward and
forward movement of the head, fore-quarters, and those portions of the body not in contact
with the ground. In character they are regular, somewhat pendulum-like, the body moving as
a whole; they last for a quarter to half a minute to intermit and be repeated again at irregular
intervals, until the animal either recovers or passes into a condition of more marked sensory-
motor disturbance or of sleep. They were observed to cease on voluntary movement or when
the animal's attention was attracted, to begin again when the disturbance was withdrawn.
The retention of the body in the semi-erect position assumed in the sitting posture is maintained
by muscular action, which when once initiated by an effort of the will is continued uncons-
ciously until the sensation of fatigue is experienced. Such actions require not only sufficient
power in the muscular apparatus concerned, but depend also for their proper maintenance
upon the stimulus derived from the muscular sense.
I would endeavour to explain the production of the peculiar movements already described
on the hypothesis that some disturbance takes place in the motor mechanism referred to. Any
cause producing inordinate action in one group of muscles or deficient action in another would
upset the state of rest maintained by the balanced action of the different groups, and lead to
the peculiar rocking movements described. There is no reason to suppose that inordinate
action of one group of muscles is due to weakness of an opposing group, for the voluntary
movements at this period show unimpaired power. Muscular mechanisms correlated in their
action so as to produce a state of balance from their combined efforts, are understood to have
the amount of their force largely controlled by impulses received from the muscular sense.
Any interference with the muscular sense would account then for undue action on the part of
one or other group of muscles, and the production of the rocking movements described. The
movements are not of the kind that would suggest their causation by irritation of the cerebro-
spinal centres, and their production on the hypothesis given is, I submit, supported by other
manifestations which may reasonably be ascribed to sensory-motor disturbance. Doses of
the drug in quantity equal to, or exceeding that amount adopted as the minimum dose,
have been observed to almost invariably produce such movements as have been described.
They succeed a period during which the animal usually evinces a degree of distress or
uneasiness, and as a rule are followed by more marked sensory-motor disturbance, or by
sleep when they cease. Though constant in occurrence and in character, they vary in the
degree of their manifestation. The scope, duration and recurrence of the movements being
more marked under certain conditions which, though not entirely independent of the quantity
of the dose, seem largely associated with the idiosyncrasy of the individual.
It appeared if the dose relative to the body weight was such as would produce marked
physiological effect short of pronounced sleep or narcotism, and if the individual idiosyncrasy
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