FIBRES OF THE INTERNAL CAPSULE OF THE BONNET MONKEY. 
65 
Table III. 
Grou]^. 
Angle of genu. 
Angle of inclination of 
axis of posterior limb 
to mesial line. 
Angle of iirclination of 
axis of anterior limb 
to mesial line. 
O 
0 
O 
I. 
134-5 
15-8 
29-7 
II. 
123-3 
20-3 
30-4 
III. 
118-9 
30-8 
30-3 
IV. 
105-1 
36-2 
38-7 
V. 
97-1 
44-8 
38-1 
VI. 
87-9 
55 
37-1 
VII. 
Not ascertainable 
40* 
VIIl. 
No genu 
57-5 
From this Table it is clear how, while the posterior limb is constantly altering its 
inclination to the mesial plane, the anterior limb moves comparatively slightly from 
the same plane in the middle three-fifths of the depth of the capsule. In other words, 
the caudate wall of the groove separating the anterior ends of the striate nuclei is 
practically vertical, though slanting outwards rapidly above, more slowly below, as is 
seen to be the case, when a frontal section is made of the anterior limb. (See fig. 2.) 
It is necessary now to give what we have regarded as the defining points of 
difference between the several groups of capsules experimented on. (See fig. 1.) 
Group I. (the highest).—Genu forms a widely open angle (13I'5°) so that the 
capsule is almost a segment of a circle. Of the lenticular nucleus only the outer 
zone or putamen appears, and it has a hi-convex outline. (See typical photograph, 
Plate 10, Experiment 35 of our series, and fig. 1.) 
Group II.—The genu is distinct and less obtuse, being 123‘3°. The second zone of 
the lenticular nucleus has not yet appeared, though the caudate reaches backward to a 
point a little posterior to the genu (the anterior part of the surcingle). (See typical 
photograph, Experiment 67.) 
The outline of the lenticular is now becoming triana^ular. 
Group III.—The angle of the genu is becoming still smaller, averaging 118‘9°. 
The second zone of the lenticular nucleus is not yet visible tliough nearly exposed. 
The caudate nucleus reaches posteriorly to the genu. The lenticular nucleus is 
becoming more triangular. In the large majority of sections the pulvinar is evidently 
free in the ventricle. (See typical photograph. Experiment 42.) 
Group IV.—This group is easily marked, since in it we have with the main 
features given under Group III., the first appearance of the second or middle zone of 
the lenticular nucleus. (See typical photograph. Experiment 31.) 
Group V.—The second zone is more marked, the white interzonal or lamellar fibres 
Probably this figure is unexpectedly low, owing to (1) the crescentic .sha])e of the cai^sule, (2) the 
number of observatious being few, viz., two. 
MDCCCXC.—B. K 
