STRUCTURAL ALTERATIONS IN NERVE CELLS 203 
in any one group. Hayem* and MAYSEat working witli the older liii>tological methods, showed 
that a similar localization of the atrophied cells occurred in the spinal cord, as a result ot section oi 
the sciatic nerve ; and Dutil, using the Nissl method of staining, again found that in a guinea-pig, 
after section of the same nerve, the characteristic changes were chiefly found in the lateral group, 
though more anteriorly. 
These observations afford evidence that the posterolateral group is especially dependent 
for the maintenance of its functional activity on the integrity of the afferent impulses. 
Secondly^ the limitation to Vllth and Vllltli post-thoracic segments. 
I find again the explanaticjn in tlie observations of Mott and Sherrington, 'i'hese 
observers have shown, in the Monkey, tliat when the Vth, Vlth, and Vllth post-tlioracic roots are 
divided, the sole of the foot is anresthetic and the defect in movement is extreme, and conversely 
that, ' if the sensory roots of the whole series of the spinal nerves belonging to a limb be severed, 
with the single exception of, in the lower limb the Vlth post-thoracic (distributed to the whole 
extent of the foot), a certain degree of impairment of movement of the limb results, which appears 
rather a weakness than clumsiness, but the degree of impairment is altogether quite slight.' 
In tile Cat the corresponding roots are tiie Vlth, Vllth, and Vlllth. Furtiier, the Vllth 
and Vlllth anterior roots are distributed to the muscles which move the foot and digits, the 
movements of which as just noticed are practically abolished after severance of the afferent roots. 
These observations show that the motor cells of the Vllth and Vlllth segments especially 
depend on the reflex impulses as an incitement to an efficient discharge. 
The escape of the sixth segment is interesting, its motor fibres are distributed in 
considerable part to the extensor muscles of the knee, and it is known that extension as a primary 
reflex movement is most difficult to obtain. 
Turning again to the records of the condition of the spinal cord after amputation, though 
exact statements as to the segments in which the atrophy of the anterior cornual cells occurs are 
not in most of the cases given, it can be seen that it is especially the lower part of the lumbar 
enlargement which is involved. 
Thus, without attempting any detailed analysis of these cases, I may instance Vulpian'sh". 
case of amputation just above the left ankle, in which the atrophy of the grey matter was found in 
the second and first sacral segments. 
In two cases of Campbell's § of amputation just below the knee the diminution of cells 
was found in Ilnd and 1st sacral and Vth lumbar segments. In cases of amputation of the thigh 
recorded by L. Clarke, || Uejerine and Mayor, 11 the diminution of cells was noted to be limited 
to the lower part of the lumbar enlargements, in those recorded by Dreschfeld** and Re^ NOLDstt 
to the lower and middle part of the lumbar region, and in a similar case recorded by Marinesco,;!:^ 
it is stated that no diminution was noted in tiie number of the cells higher than the level of the 
* Hayem. ' Arch. <le Phys. norm, et pathol.,' p. 504. 1873, 
t Mayser. ' Arch. f. Psychiatric,' vii, p. 539. 1877. 
J Vulpian. 'Arch, de Phys. norm, et pathol.,' p. 443. 1868. 
§ Campbell. ' Proc. Liverpool Med. Institution.' 1896. 
II L. Clarke. ' Med. Chir. Trans.,' li, p. 249. 1868. 
^ Dejerine et Mayor. ' Comptes Rendiis,' 1S78. p. 24 
** Dreschfeld. ' Journ. of Anat. and Physiol.,' xiv, 
p. 424. 1879. 
ff Reynolds. ' Brain,' xxxvi, p. 494. 1887. 
JJ; Marinesco. ' Neurol. Centralb,,' p. 463. 1892. 
