10 
(iEOliGE E. NICHOLES. 
have coinniencecl with the work of Studiiicka, wlio, in 1899, 
announced that he had observed the fibre in a large number 
of forms. His description, however, relates principally to 
Petromyzon. He discovered the posterior end of the fibre 
in a tangled condition somewhat similar to that described by 
Sanders in Myxine. He expressed the opinion that it was a 
pre-formed structure, and stated that he found it to be homo- 
geneous, affording no evidence of internal structure. He 
concluded that it was non-nervous, and probably produced 
as a secretion of the ependymal epithelium of the canalis 
centralis. He failed, however, to observe its connection 
anteriorly with the sub-commissural organ (although, in 
Petromyzon, he succeeded iu following it forward to a 
point immediately beneath the posterior commissure), and 
he supposed, erroneously, that the anterior end of the fibre 
was free and possessed of the power of growing forward. 
Six months later there appeared the first of Sargent’s 
])reliminary papers. In this paper (’00) he states (p. 41) 
that “ the course of Iteissner’s fibre through the ventricles 
to its termination anteriorly has been most thoroughly 
studied in Teleosts, where it has been followed continuously 
in Cynoscion, Pomatomus, Morone, Ami a and Salvelinus. 
The fibre has been followed to its termination in 
the torus also in llaja, Lepidosteus, Nectuims, 
Alligator, S c e 1 o j) t e r i s , g a r t e r - s n a k e, and less 
completely in many other species including the 
mouse and pigeon.” (The spaced type is mine.) 
It will be sufficient comment upon this statement to recall 
the fact that the torus Ion gitudinalis is a structure 
peculiar to the brain of bony fishes, as was shown by Pabl- 
liuckhard long since (’84). What Sargent supposed to be 
the torus 1 o n gi t u d i n al i s, and labels as such in his text- 
fig. 1, is evidently the ]>osterior commissure. 
Describing the course of Peissner’s fibre he says (op. cit., 
]). 42) ; “ Passing along the median fissure of the torus lor 
one half to two-thirds its length and close to its surlace 
(tigs. 8, 9), the fibre passes beneath the membrane which 
