PHYSIOLOGICAL ACTION OF ATROPINE. 
105 
nerves of both irises in so concentrated a state, as still to be 
able to cause dilatation of the pupils. Whether in the latter 
two examples the narcotic acted on the periphery, or on the 
roots of the nerves, it is impossible to say ; but, certainly, in 
the case where the quantity of atropine employed was so 
minute as to have just sufficient strength to dilate one pupil, 
and that the contiguous one, we are constrained to admit the 
possibility of the atropine having directly paralysed the peri- 
phery of the nerve. The origins of the nerves supplying the 
opposite eyes are so close together, that we cannot suppose, 
with any degree of feasibility, the atropine to have been 
transported by the general circulation to the root of the 
nerve on which it acted ; had it been so, we must have had 
dilatation of the pupils of both eyes ; for it is natural to 
suppose, that a similar quantity of poisoned blood would 
simultaneously arrive at the roots of both nerves. In Expe- 
riment 2, where the narcotic directly entered the general 
circulation, as well as in Experiment 4, where such an excess 
of atropine was absorbed by the conjunctiva, that not only 
the contiguous, but also the distant pupil became dilated — 
the supposition of the narcotic having acted upon the origins 
of the nerves, appears to be not altogether unwarranted. 
Experiment 5 . — Into the left eye of a cat, whose pupil on 
that side had become permanentl} 7 contracted in consequence 
of excision of about an inch of the left cervical sympathetic, 
a drop of the solution of atropine was allowed to fall. In a 
short time the adjacent pupil became half dilated , and, 
although more of the solution was afterwards added, com- 
plete dilatation could not be induced. 
This agrees with “the case narrated by Dr. Gairdner, in 
which contraction of the pupil was associated with an 
aneurism at the root of the neck, .... and where repeated 
doses of belladonna, given internally, dilated both pupils. 
But it was observed throughout the experiment, that the 
affected pupil continued smaller than the other;” just as we 
have seen in Experiment 2. 
Experiment 6. — The third nerve of a cat was divided at the 
point of exit from the sphenoidal fissure ; the pupil on the 
same side immediately became dilated, and remained so. 
The addition of a couple of drops of atropine solution was 
not observed to increase the dilatation of the pupil, as we 
expected, from the observation of Dr. John Struthers, who 
noticed that in the human subject belladonna acts upon 
pupils already dilated from some diseased condition of the 
