ON THE FUNCTIONS OF THE CEREBRAL CORTEX. 
5 
results of our experiments upon the ablation of this part and those of Munk we are 
unable to explain otherwise than by supposing that sufficient care was not taken by 
Munk to localise the lesion by the adoption of the precautions of modern antiseptic 
surgery. Thus he speaks of operations upon this region ir the Dog as taking two or 
three weeks to heal in the most favourable instances, and even then as discharging 
pus ! And, although according to this author Monkeys appear to bear the removal of 
portions of the brain far more easily, so far as the after-process of healing is concerned, 
than Dogs, yet it must be assumed that there will be a greater or less amount of 
inflammatory extension of the intended lesion in all cases in which antiseptic 
precautions are omitted. Indeed we do not hesitate to affirm, on the strength of 
the evidence affi^rded by two or three of our cases in which the wound, although at 
first aseptic, subsequently became septic, that all experiments upon the brain in which 
these precautions are neglected are not only liable to be lacking in definiteness and 
precision, but may even be expected to yield illusory results. 
No doubt the same remark will apply to the earlier experiments of Ferrier, which 
were performed without the employment of such precautions, and were obviously 
followed in mauy cases by inflammatory extension of the original lesion. The 
argument that such extension must have taken place, which with other arguments 
Munk urges with somewhat unnecessary bitterness (' Functionen der Grosshirnrinde 
— Erste Mittheilung '), attempting to discredit the whole of Ferrier's work in this 
direction, can be used with equal force against many of the results obtained by 
himself. 
II. — Results of Experiments upon the Motor Region of the Cerebral Cortex. 
Results of excitation of the external surface. — Excitation of the external surface 
of the hemisphere has in our hands yielded results which are generally similar 
to those described by Ferrier,'" which they may be said to extend and confirm, with 
some exception as to detail. It will be remembered that besides certain areas close 
to the great longitudinal fissures, which are concerned with movements of the hind- 
limb, the principal movements obtained by Ferrier by stimulation of the excitable 
portion of the external surface were : (l) On the middle of the frontal lobe — 
movements of the head and eyes. (2) Just behind this area on the ascending frontal 
— movements of the hand and arm. (3) On the ascending parietal — movements of the 
fingers and wrist. And (4) around the lower end of the fissure of Rolando, including 
parts of both central convolutions — movements of the face, jaw, and tongue (several 
of these movements being still further differentiated). Our experiments show that 
the motor portion of the cerebral cortex may be mapped out into a certain number 
of main areas, each of which is chiefly concerned with the movements of a particular 
part or limb, and in some of which certain centres concerned with more specialised 
* ' Proceedings of the Royal Society,' vol. 23, 1875, p. 409. 
