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rapidly diminishing frequency as the animals became accustomed to 
their surroundings, practically never occurring after they had been in 
the tank for a week. 
In the specimens upon which SARGENT based his conclusions, it 
was remarked that they became sluggish upon the third day and died 
upon the fourth or fifth day from meningitis, whereas in the greater 
number of my experiments, recovery was setting in by that time. As 
already stated, none of the subjects died either from the operation or 
its sequelae, the only loss being that of two which were given an 
overdose of anesthetic. 
Experiments upon the dogfish were limited to three, performed 
upon specimens all about sixteen inches in length. Of these, one, as 
already stated, died without recovering from the chloroform, and the 
behaviour of the remaining two during the early days of the experiment 
differed markedly, although both behaved precisely as did the skates 
immediately on reviving from the effects of the anesthetic. 
One (No. 2) then became somewhat sluggish and rested upon the 
floor of the tank exhibiting marked lateral curvature of the body and 
tail. The end of the tail, however, was supported lightly upon the 
lower border of the caudal fin in a manner perfectly normal. By the 
third day it had seemingly learned the limits of its tank and the 
running full tilt into the enclosing walls became a much less frequent 
event. Upon the fourth day the end of the tail was first observed to 
be slightly lifted so that the caudal fin no longer touched the floor 
of the tank. The animal became more and more lethargic as time 
went on, and from the fourth day onward until the eleventh after the 
operation it passed almost all the time resting upon the bottom, with 
its body curved and its tail supported upon the sloping surface at the 
junction of the wall and floor. On the latter day it lay upon the 
bottom of the tank well away from the wall, with its body in short 
wavy curves and its tail distinctly uplifted so that the ventral surface 
of the caudal fin cleared the floor by more than two inches. Once 
only during this time was it observed with its tail stretched behind 
it normally in a straight line. This occurred for a short time upon 
the eighth day but it soon reverted to the characteristic bent condition. 
The tail remained uplifted for several days but on the sixteenth day 
this uplifting was much less marked, and by the following day, when 
the specimen was killed, it had practically disappeared. 
The second specimen (9) showed for six whole days after the 
operation an extraordinary restlessness, and never once during the 
whole of that time could I succeed in observing it at rest. Upon the 
