82 
GKORGE E. NTGHOIJ;S. 
contribute a considerable brancli if Sargent’s account were 
correct. 
Sargent devotes some space (’01, ’04) to the consideration 
of the physiology of the “ optic reflex apparatus,” and gives 
an account of certain experiments performed by him upon 
living sharks. He says (’04, p. 231) that “ these experiments, 
though incomplete, show clearly, I believe, that when 
Reissner’s fibre is severed the power to respond quickly to 
optical stimuli is lost,” which, eveu if it were established, is 
not at all the same thing as proof that the slowness of response 
said to have been observed is due either wholly or partly to 
the retardation of an optical stimulus. 
He goes on to compute (’04, p. 240), from theoretical con- 
siderations, that the saving of time effected in the transmission 
of an optical stimulus along the short-circuit ” path afforded 
by Reissner’s fibre would probably amount to at least O'OIG 
-f X seconds (where x is the delay in one cell-body), or 
approximately a saving of less than one fiftieth of a second, 
which is surely an insignificant result for such an elaborate 
and special apparatus. 
In his earlier paper (’01) Sargent had denied the existence 
of the fibre in blind animals, and stated (op. cit., p. 451) 
that “ experiments are now in progress to determine the 
effect of artificial extirpation of the eye on this apparatus.” 
The value of such experiments is obvious if, as Sargent 
believed, the fibre were absent in blind animals, and it would 
be of considerable interest to know what results were obtained, 
but in none of Sargent’s later works is there any farther 
reference to these experiments, and, as shown above, Sargebt 
had subsequently to admit the existence of a fibre of Reissner 
in some blind animals, although, as already noted, he 
endeavoured to explain it away as being probably a case of 
the fibre functioning solely as an olfactory reflex apparatus. 
In discussing the work of Housei*, or rather that part of it 
which relates to Reissner’s fibre, it is necessary first to con- 
sider to what extent his conclusions may have been influenced 
