PARALYSES IN DOGS 109 
reflex and sphincteric control, all accounted for by lesion in 7th lumbar 
and Ist sacral segments. Slight paralysis of right paw also explained 
by damage to right anterior roots. 
Experiment 78. (Figs. 24 and 25.) Impairment of control of motion, 
point and heat-pain sensation in tail, together with impairment of anal 
reflex and bladder control, all accounted for by lesion in the 7th lumbar 
segment. 
Correlation of data derived from individual experiments 
A. Control of joints. Upper leg centers are mostly in the 
5th and 6th lumbar segments, that is, about the level of the 4th 
dural root exit. Lower leg centers are in the lower 6th and the 
7th lumbar segments, that is, at the level of the 5th dural root 
exits. Nuclei of the external popliteal, the internal popliteal 
and the tail are somewhat circumscribed and relatively isolated, 
and the nucleus of the external popliteal is, as a whole, higher 
than that of the internal popliteal. There may be some over- 
lapping of nuclei, but in one portion of the cord, namely, the mid- 
dle 6th lumbar segment, there seem to be relatively few centers, 
the nuclei of the upper and lower leg seeming to be respectively 
above and below this apparent gap. (Possibly the hamstring 
centers lie here.) 
It is suggested that the anterior columns contain fibers from 
the brain which convey volitional impulses. 
B. Knee jerks. Its extinction or weakening is consistent with 
corresponding damage to either the roots or grey matter of the 
5th and 6th lumbar segments. 
C. Sensation. As to point sensation of the whole leg, the 4th 
and 5th posterior roots seem important links in the afferent chain. 
As to heat-pain sensation of the paw (studied by immersion in 
hot water), the test was omitted in three of the experiments and 
was always accompanied by loss of point sensation. In one case 
however (Experiment 70), point sensation was lost without 
corresponding impairment of heat-pain sensation in paw. 
D. Anal reflex. This test was omitted in one case, found 
impaired in seven and normal in two. 
E. Control of sphincters. Their centers lie below the 6th 
lumbar segment. It is suggested by comparison of two cases 
