142 Drs. F. W. Mott and W. D. Halliburton. [Nov. 14, 
Ziehen, that it is homologous with the sulcus centralis of the primates, for the area giganto- 
pyramidalis extends behind it. In support of this argument he has also examined the 
brains of two monkeys, Periodictus potto and Propithecus coronatus. The former has a 
well-marked central sulcus, and this is the caudal boundary of the area giganto- 
pyramidalis, as well as of the excitable area. In Propithecus, the central sulcus is repre- 
sented by a small dimple only, very like what we have labelled sulcus 1 in the Lemur. 
In Propithecus, however, it forms the caudal boundary to the excitable area, and to the 
area giganto-pyramidalis. He therefore argues that in this monkey it is the true homo- 
logue of the central fissure, and that the apparently similar dimple in the Lemur’s 
brain cannot be the same, since it lies within the excitable area and the area of large Betz 
cells. 
Max Volsch’s* work was apparently undertaken to prove the correctness of Professor 
Ziehen’s view. He concludes that the general arrangement of the motor centres appears 
to agree with that of the primates, and that they are situated in front of the small sulcus 
we are discussing, and which he therefore regards as the representative of the central 
fissure. He, however, wisely remarks that the results of only one experiment cannot lead 
to far-reaching conclusions. 
Flatau and Jacobsohn} regard the anterior end of the lateral fissure as homologous 
with the central fissure, and look upon the little sulcus (1) as a rudimentary pre-central 
sulcus. 
Kxtirpation Hapervments. 
The extirpation experiments were four in number. The operations were 
performed under ether anesthesia, and with strict antiseptic precautions. 
Healing took place by the first intention in all cases ; the paralysis exhibited 
after the operation was not pronounced in any experiment, and soon passed 
off; this transitory nature of the paralysis has been frequently noticed before, 
especially in animals low in the scale. The animals were finally killed by 
chloroform about a fortnight after the operation, and the parts which were to 
be subjected to microscopic study were then placed in suitable preservative 
fluids. 
The following are short protocols of the four experiments performed :— 
Lemur 4. Lemur macaco.—The motor area was removed as completely as possible on 
the right side, except that the part below the sulcus rectus and lateral fissure, which 
governs mainly head, eye, and ear movement, was left intact. Immediately after the 
operation there was conjugate deviation of head and eyes to the right, and the left pupil 
was rather larger than the right. These effects were transitory. The paralysis of the 
left limbs had passed off to a great extent two days later ; the fingers and toes on this 
side were, however, not so well used in climbing as those on the right side. The animal 
was killed by chloroform 14 days after the operation, by which time it was difficult to 
recognise any paralysis. The grip of the left hand was not noticeably weaker than that 
of the right. 
Lemur 7. Lemur catta.—A large amount of the motor area was removed on the right 
* Loe: cut. 
+ ‘Handbuch der Anatomie u. Vergl. Anat. des Zentral-Nervensystems der Saugethiere,’ 
1899, 
