86 
THOMPSON YATES LABORATORIES REPORT 
one instance only. Concordantly with this the Vlth cervical in Macacus I have found to supply 
the diaphragm regularly (examination by degeneration and ' teasing,' as well as by excitation 
method). In a Macaque in which the Vllth right cervical nerve had been severed twelve days, 
I failed to discover degenerate fibres in the phrenic trunk. In Man the phrenic ' arises mainly 
from the IVth nerve, also receiving in the majority of instances an additional root from either 
the Ilird or the Vth nerve ' (Thane). On the other hand, in his ' Anatomy of Domesticated 
Animals,' Chauveau describes the phrenic as arising mainly from the Vlth and Vllth nerves, 
with a subsidiary branch from the Vth. As judged by the root-constitution of the phrenic nerve, 
therefore, the muscles innervated by the brachial region of the cord are more prefixed in Man 
than in the other Mammalian types coming under observation, including Monkey. It may be, 
therefore, that in a certain number of human brachial plexuses the Ilnd thoracic does not 
contribute to the innervation of the hand muscles ; and certainly in Macacus the amount of 
contribution by it varies, for I have in some individuals failed to evoke contraction of the deep 
flexor of the forearm through it, though this is often readily done. On the other hand, again, it 
is possible that the segmental position of diaphragm (or rather of phrenic nerve) may vary 
independently of that of the musculature (or nerve-trunks) of the limb ; but this supposition is 
not in harmony with the rule I found deducible from the lumbo-sacral plexus, viz., ' the shifting 
up or down of the region of outflow along the cord applies to all the efferent fibres of that 
lengtli ' ; in other words, although each muscle (nerve-trunk) is displaced absolutely, it is not 
displaced relatively to its neighbours. Langley's researches on the Sympathetic shew that, to 
use my own nomenclature, the cervical sympathetic is more prefixed in the Cat and Dog than in 
tlie Rabbit ; a fact in accord with the not infrequent absence of the contribution from Ilnd 
thoracic noted above in the Cat (and Dog). Klumpke's conclusion from clinical data, that in 
Man the dilatators of the pupil emerge from cord entirely in the 1st thoracic root, is almost 
certainly not correct. We know of no type, including Monkey, in wlu'cli the outflow of dilatators 
is limited to one root, and Brun's case shows that in Man some leave by a root lower than 1st 
thoracic. Yet Klumpke's evidence makes it probable that they leave in Man chiefly by 1st 
thoracic. If so, then the evidence from the sympathetic, and also from the phrenic, points to the 
nerves and muscles of this region in Man being prefixed, as compared with Macacus and the 
laboratory types. This fact may be remembered in connection with the reduction of sensory 
roots which seems to be in progress at the top of the neck ; the ganglion of the hypoglossal, and 
that of the 1st cervical roots, both present in Ruminants, the latter present in the Cat and Rabbit, 
have both disappeared in Macacus and in Man. 
As to the spinal skin-fields of Macacus and of Man, clinical opportunities arise for 
observing some of the latter sufficiently to give ground for brief examination of the correspondence 
between the two. The opportunities of the bedside have afforded the basis for the admirable 
papers of Thorburn, Head, James Mackenzie, Starr, and Kocher. In regard to the IVth 
cervical, Starr's determination of the posterior edge tallies closest in general level with that 
of Macacus ; Head's determination in shape of contour, the curious double shoulder peak of 
Macacus, appearing with fidelity in Man. In regard to the Vth cervical, there is close 
