206 
DR. F. SEMON AND MR. Y. HORSLEY ON AN INVESTIGATION 
But we may observe incidentally that we are naturally inclined to regard that small 
area of the medulla from which adduction can be produced as a transit-station for the 
corresponding cortical, and as a centre for reflex phonatory impulses. Whether this 
is really so the future will show. What is, for the present, of more practical import 
in this connection is how far the bulbar apparatus for the larynx is bilateral or 
unilateral in its composition. It will be seen directly that we have obtained from 
the one half of the medulla oblongata both bilateral and unilateral eflects, that is, 
as far as they go the bilateral effect is for the most part complete, sometimes, i.e., when 
the electrodes are moved outwards, with a preponderance of movements on the part 
of the cord on the same side, and the unilateral effect is of course movement of the 
cord on the same side as that stimulated. 
We shall discuss the results then from these two standpoints, viz., (1) the bilateral 
effect, and (2) the unilateral effect. 
We have only made observations on the Carnivora, and in this respect it is 
interesting and important to note that the results in the Cat are not different from 
those in the Dog. In fig. 9 is given a photograph of the floor of the fourth ventricle 
in the Dog, the calamus scriptorius {c.s., fig. 9) is well seen bounded laterally by the 
fasciculus gracilis passing up on each side towards the restifoim body with the ala 
cinerea (a.c., fig. 9) well marked. The cerebellum has been divided and the right half 
removed, so as to expose the lower surface of the inferior peduncle completely, and 
only the upper part of the inferior vermiform process is seen to be in contact with the 
floor of the ventricle. 
Within the area thus exposed are included all the movements of the vocal cords 
which may be reasonably attributed to phonation, and also almost all which are 
connected with respiration. However, in accordance with what we have stated above, 
we shall now proceed to describe the movements of the vocal cords independently of 
the function they may be supposed to subserve. 
1. Adduction .—Closure of the glottis is sharply and invariably produced when the 
upper margin of the calamus scriptorius, i.e., the nucleus of the spinal accessory nerve, 
is stimulated, and the same thing is observed if the electrodes are carried outwards 
and upwards along the margin of the posterior pyramid for about 3 mm. from the 
middle line. This action is distinctly bilateral. 
Immediately above the calamus, in the situation of the ala cinerea, abduction is 
invariably produced. This movement, like that of adduction, is also absolutely 
bilateral and persistent. It extends upwai’ds as high as the line drawn horizontally 
across the fourth ventricle at the transverse level of the upper end of the representa¬ 
tion of the adduction. (See fig. 9.) Above this point, especially in the middle line 
as high as the level of the eighth nerve, excitation evokes movements of the cords 
about the cadaveric position (see dotted area, fig. 9), which may be looked upon as 
either a confusion or imperfect adduction. This movement is strictly bilateral. 
We have obtained unilateral adduction of the vocal cord on the same side b}?" 
