Influence of the Nervous System 645 
orated Herbst’s observation that the level of the injury deter- 
mined the kind of regeneration; for, the removal of the entire eye, 
stalk included, resulted in an heteromorphicstructure; when the dis- 
tal end, including about one-third of the ganglia, was cut out, an eye 
regenerated. When, however, Steele amputated intermediate 
between these levels, no regeneration whatsoever occurred. If 
the presence of the sensory ganglia, in whole or in part, conditioned 
the regeneration of the decapod eye, it is difficult to understand 
why they should not exercise their power in other species of deca- 
pods, and in certain mollusca (Carriére); and if the ganglia are 
necessary in the regeneration of the eye, why are they not equally 
important in the regeneration of the antennz of the same animal? 
Our evidence concerning other adult animals will be found in 
each of the following sections. 
Of special interest are Wolff’s experiments wherein he sought 
to ascertain “whether the hind legs of a Triton, whose nervous 
connections with the central nervous system had been severed, 
would regenerate in the same manner as in an uninjured animal.” 
He removed the nerve cord from the plexus cruralis of a num- 
ber of the animals of which but three survived. These regener- 
ated the missing leg. He then sought to remove both motor and 
sensory cells from the plexus. Only six animals survived. ‘These 
also regenerated, but the leg contained a reduced number of toes. 
Of these six individuals, he tells us, four displayed some degree of 
movement within three months after the operation, 1. e., there was 
a return of sensory and motor functions of the limbs. Neverthe- 
less the malformation persisted. ‘Die oben erwahnten sechs 
Ausnahmen (haben) mit der denkbar gréssten Bestimmheit einen 
Einfluss des Central-Nervensystems auf den regenerativen Vor- 
gang nachgewiesen.” He also drew the conclusion that “Diese 
Falle lieferten einen Beweis von der Einwirkung des Nerven- 
systems auf morphogenetische Vorgange.” His final position seems 
to be that during the early stages in regeneration no nervous stim- 
uli are needed, but that later, unless they be present, atypical 
structures are produced. 
Barfurth ’o1; Wintrebert ’03; Godlewsky ’04; Hines ’o5 also 
made some experiments on adult animals, with the same general 
