i ae Ss) al 
ea 
1907.| Localisation of Function in the Lemur’s Brain. 145 
a lower level in the medulla is reached than in Lemur 7, and they can be 
followed all the way down the cord to the lumbo-sacral region, as shown in 
figs. 14,15, and 16. There is, indeed, almost as heavy a degeneration in the 
crossed pyramidal tracts of the cervical region (fig. 14) as in the pons and 
medulla. Moreover, the degenerated fibres have not left the crossed pyramidal 
tract in the mid-dorsal region, for there are nearly as many degenerated fibres 
seen in the sixth dorsal segment (fig. 15) as in the eighth cervical (fig. 14). 
Most of the degenerated fibres can be seen leaving the pyramidal tract in the 
lumbo-sacral region ; when fig. 16 (section at the fifth lumbar level) is com- 
pared with fig. 15 (section at the sixth dorsal level), a great diminution in the 
number of degenerated fibres 1s seen. 
We have not presented any diagrams of our examination of the central 
nervous system in the case of Lemur 4. It was thoroughly examined, and 
the results were confirmatory of those found in the other cases. Lemur 4 
belonged to a different species from the other three, but this makes no differ- 
ence to the course of the degeneration. In this case, also, the lesion was more 
extensive, including both arm and leg cortical areas, so the degeneration was 
more extensive, and showed practically a combination of the results noted in 
Lemurs 7 and 8. 
In no case were we able to follow degenerated fibres to the anterior horn ; 
in some sections they could be seen lying as small compact bundles within 
the base of the posterior horn. 
As in the lower apes, there is no direct pyramidal tract in the spinal cord - 
of the Lemur, although it may be mentioned that one finds generally a few 
(homo-lateral) degenerated fibres in the crossed pyramidal tract of the same 
side as the lesion. 
Summary. 
1. The brain of the Lemur has a simple convolutional pattern, and the 
fissures are few and for the most part shallow. 
2. The motor areas are limited to the central region of the cortex, and 
details of the localisation by the method of stimulation are given in 
Plate 2 (fig. 1). 
3. Extirpation of the excitable areas is followed by transitory paralysis of 
the corresponding regions on the opposite side of the body, and by degenera- 
tion of the tracts which pass to the bulbar or spinal grey matter which 
controls these movements. Degeneration also occurs in commisural (callosal) 
and association tracts in the cerebrum. . 
4, The motor areas are characterised histologically by the presence of Betz 
cells. Localisation by histological study is therefore possible, and the close 
