Houser, Zhe Neurones of a Selachian. 163 
complications. THORNDIKE (’99) has made at least a begin- 
ning in this field for the teleosts. This observer placed a screen 
with but one opening across the course in which Fundulus de- 
sired to swim. He found that after several repetitions the 
animal ‘‘learned to get out,’’ Here, it would seem, there was a 
true memory of previous activities in the absence of any ner- 
vous pallium at all, a very suggestive fact in connection with the 
intepretation placed in the present paper upon the pallium of 
Mustelus. An extension of the scope of experimental work on 
the fishes will certainly prove fruitful for comparative neurology 
in so many ways that the writer feels impelled to bespeak a 
larger place for this kind of work in our investigations. 
Since the promulgation of the neurone concept of Wat- 
DEYER in 1891, no work has demanded more critical attention 
than that on the ultimate fibrillar structure of the nervous sys- 
tem, studies with which the names of ApATHy, BETHE, and 
Nissi will ever be connected. An investigation of neuro-fibrils 
obviously lies beyond the bounds set for the present research, 
and observations concerning them in Mustelus must await an- 
other opportunity for expression. In the meantime, I would 
join with the protest made by A. MEYER (’99), PARKER (1900), 
and VERWORN (1900) against the tendency to elevate the results 
of specific methods into an exclusive dogma. Although spoken 
from a different vantage-point, the words of Goxicr (1900) may 
well be quoted here: ‘‘The knowledge which we possess, either 
anatomical or physiological, is not yet such as to permit us to 
interpret with certainty the greater number of the facts dis- 
covered, much less to attempt doctrinal constructions of a high 
order on the functional mechanism of the nervous elements.” — 
