124 THOMPSON YATES LABORATORIES REPORT 
activity of the isolated cord itself is soon depressed by anaesthetics; and an experiment in my 
former paper* illustrated the ease with which chloroform lowers even the tonic activity of the 
spinal nerve-cells. My plan has been, therefore, after transection of the cord, to somewhat relax 
the general anaesthesia, and then to examine reflex action in the isolated portion of cord, all parts 
still connected with it having of course, ipso facto^ become insentient, pace the unproven Rucken- 
marksseele.\ In most cases the transection was made shortly prior to examination of the reflexes, 
but in some cases periods of recovery were allowed, extending at longest to six months. For 
excitation, mechanical, thermal, or faradic stimuli, usually approximately minimal, have been 
used. 
In many cases it was noted whether the limb-plexus belonged to the prefixed or postfixed 
class. This it seemed necessary to do, as individual variation so frequently affects the relation 
between motor root and limb muscles (Eckhard,! Frog ; Langley,§ Cat ; Sherrington,]! 
Frog, Cat, and Monkey), and analogously disturbs the relation between skin and spinal ganglion 
(SherringtoNjH Frog, Cat, Monkey). The range of segmental oscillation can allow 'in the origin 
of a root-filament a sufficient displacement to remove it from the upper to the lower half of the same 
root, or from the lower half of one root to the upper half of tlie next below,' or conversely. Progress 
with the inquiry into reflexes showed, however, that two factors largely reduce the importance of 
individual particularities of distribution of the nerve-roots in regard to reflexes. One of these factors 
lies in the rule which I have already laid down, that each root-filament, although its segmental 
level be displaced absolutely, yet is not displaced relatively to its neighbours, ' the shift applying in 
the same sense to an extensive fore-and-aft series of filaments, and those of the dorsal and ventral 
roots tending to be similarly affected.' ** The other factor lies in the rule of ' spatial monotony,' 
to be discussed later. 
Reflex Movements Characteristic for the Individual Afferent Spinal Roots of Macacus. 
The initial step of the inquiry has been to determine for the several dorsal spinal (afferent) 
roots the particular spinal paths easy of access through them. I have attempted to carry this out by 
noting the limb movement most easily provoked by excitation of the proximal end of each on the 
spinal side of the root-ganglion. In the regions of which I chiefly treat the vast majority of the 
afferent fibres are, in Gaskell's sense, somatic. Besides, there is evidence that between somatic 
afferents and splanchnic efferents a high intra-spinal resistance exists.tt I have, therefore, with few 
exceptions, disregarded sympathetic out-channels, believing the paths of least resistance, which 
were my object, would not lead greatly in their direction. 
The movements obtained by excitation (minimal, or not far removed from minimal) of 
the spinal ends of dorsal (afferent) roots have been as follows [Macacus) : — 
XlVtli Post-thoracic Root. — Tail lifted and generally abducted, very often toward the opposite 
side ; no movement of arms or of limb. 
* ' Journ.of Physiol.,' vol. 13, p. 671. 
■f Pfliiger, ' Die Sensorischen Functionen des Riicltenmarks.' 
Berlin, 1853. 
I ' Zeits. f. rat. Med.,' vol. 7, p. 306, 1849. 
§ ' Journ. of Physiol.,' vol. 12, p. 366, 1891. 
II 'Journ. of Physiol.,' vol. 13, p. 621, 1892. 
f ' Phil. Trans.,' B, vol. 184, 1893. 
** 'Journ. of Physiol.,' vol. 13, 1892. 
ff Sherrington, 'Journ. of Physiol.,' vol. 13, 1892, p. 732. 
