732 REPORT—1904. 
arc involved. For in the lateral part of the lateral column one has proved 
by, ‘successive degeneration’ that long fibres exist directly connecting the 
spinal segments of the shoulder with the spinal segments containing the motor 
neurones for the flexor muscles of the hip, and knee, and ankle. The 
course of these long fibres can be traced}and their number counted. We thus 
Fig, 1. The Scratch Reflex, 
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—The ‘ receptive field,’ as revealed after low cervical transection, a saddle-shaped area of dorsal 
skin, whence the scratch reflex of the left hind limb can be evoked, ir marks the position of 
the last rib. 
B.—Diagram of the spinal ares involved. 1, receptive or afferent nerve-path from the left foot; 
R, receptive nerve-path from the opposite foot ; Sa, s8, receptive nerve-paths from hairs in the 
dorsal skin of the left side; rc, the final common path, in this case the motor neurone to a 
flexor muscle of the hip ; Pa, P8, proprio-spinal neurones. 
arrive at the following reflex chain for the scratch reflex: (i) The receptive 
neurone (fig. 1 B, sa), from the skin to the spinal grey matter of the corresponding 
spinal segment in the shoulder. This is the exclusive or private path of the arc. 
(ii) The long descending proprio-spinal neurone (fig. 1 B, pa), from the shoulder 
segment to the grey matter of leg segments. (iii) The motor neurone (fig. 1 B, Fc), 
from the spinal segment of the leg to the flexor muscles, This last is the final 
