Influence of the Nervous System 647 
nerves, and can therefore be readily distinguished from them. 
These nerves will be referred to as plexus nerves I, II and III, 
respectively. [hey branch to form the obturatorius and cruralis 
on the one hand, and the ischiadicus on theother. ‘The last again 
divides into the peroneus and tibialis, etc., of the leg. 
Various attempts were made to sever the nerve connections of 
the hind legs. ‘The difficulty was in making certain that a// nerve 
impulses to the amputated end of the limb were removed either 
permanently or for a considerable time at least. For it is well 
known that the cut ends of nerves may reunite, or secondary 
connections may be made. 
eae r 
See a oS — = 
ia ‘~ xe SS 
ae — 
io hee) Ae | 
| 
t 
| 
— 
NI { 
\ 
Cc! G 
L--7 
Fig. 1 Distribution of the nerves to the hind leg and tailof Diemyctylus viridescens. Partly schem- 
atized. P, pelvic region of body; 7’, tail region. Innervation same throughout the tail. L, leg 
Cl, cloaca. 1, 2, 3, first, second and third nerves of lumbo-sacral plexus. G, sensory ganglia. 
The simplest operation consists in cutting one or more of the 
large nerves of the leg. This method is totally inadequate because 
(1) union of the cut ends might possibly take place by “first 
intention,” i. e., immediately after the operation; (2) connections 
between the central and peripheral nerves or their branches may 
be established; (3) the central nerves may grow, independent of the 
old path, into the peripheral region. 
When a piece of the nerve is excised, immediate union of the 
two ends is prevented, yet this method of operating is open to the 
first and second objections mentioned above. A third method, 
and the only one worth serious consideration, consists in destroy- 
