198 
DR. F. SEMON AND MR. V. HORSLEY ON AN INVESTIGATION 
of course, possess considerable interest. Fi’om anatomical reasons these resolve them¬ 
selves under two headings— 
(1) Upward Movement of the Larynx, 
(2) Downward ,, ,, ,, 
(1) Upward movement of the larynx we noted to occur only in front of the Fissure 
of Rolando, between it and the small secondary sulcus marked v in figure. 
This movement is associated with swallowing and mastication, these actions 
being (Beevor and Horsley) represented in the strip of cortex thus indicated. 
Clearly, in this association, we have only the completion of the observed representation 
of these complicated acts. 
(2) Downivard movement of the larynx we obtained by exciting the cortex just 
behind the Fissure of Rolando between that sulcus and a line parallel to it, drawn 
from the lower end of the intraparietal sulcus to the Fissure of Sylvius. 
Once we observed confusion between the movement of the larynx upwards and 
downwards to occur at this point, the downward direction predominating. 
Einlepsy. —We have frequently observed epilepsy to follow excitation of the cortex 
in this region. At the commencement of the fit, the vocal cords are strongly 
adducted, often with tremors, i.e., confusion between adduction and respiratory (?) 
abduction, this persisting during the tonic stage. Then, in the subsequent clonic 
stage, the movement of adduction alone occurs as single spasms and ceases, of course, 
often suddenly. 
Carnivora . — Dog. 
Phonation. —The following account applies only to the adult animal ; we shall speak 
later of the differences which are caused in the cortical representation according to the 
age of the individual examined. The nomenclature of the sulci employed will be that 
given by Langley in his admirable paper on this subject,'"" except that for brevity we 
shall speak of the anterior limb of the sigmoid gyrus as the priecrucial gyrus, and 
similarly of the posteiior limb as the postcrucial gyrus. In the original description 
given by KRAUSEt of the cortical representation of the movements of the vocal coi-ds, 
that author localised the focus of the representation to be situated in the prmcrucial 
gyrus [or, as he called it, following Munk, the gyrus praefrontalis (Owen),] just where 
that gyrus terminates below in a narrow pillar or isthmus connecting it with the 
anterior composite gyrus. At this point he found that excitation, as a rule, produced 
bilateral adduction of the cords ; this we have completely confirmed, but we have also 
found that while the spot indicated is a focus, nevertheless slight adduction can 
be obtained by excitation of the whole of the lower two-thirds of the prmcrucial 
gyrus, and also a few millimetres of the upper extremity of the anterior composite 
gyrus. 
* ‘ Journal of Physiology,’ December, 1883, p. 248. 
t • Archiv f. Anatoiuie nud Pliysiologie, Phys. Abth.,’ 1884, p. 203. 
