STRUCTURE AND DEVELOPMENT OF REISSNER’s FIBRE. 107 
and Ayers as the fourth ventricle, represents actually but a 
small portion of the aqueductus Sylvii, and I have 
preferred, for that reason, to speak of it as the sinus 
inesocoelicus. 
Sterzi (’07) identifies it correctly as the cavity of the mid- 
brain, he appears not to have noticed the istliinic canal in 
Myxine, although he saw and called attention (op. cit., p. 539) 
to the occurrence of small scattered spaces that continue 
backwards from it towards the upper canal of the spinal cord. 
He, so far as I can find, makes no reference whatever to the 
occurrence of Reissner’s fibre. 
Sai'gent (’04) quotes that part of Sanders’ descriptions 
which I'elates to the course of Reissuer’s fibre in the brain, 
and dismisses it without further comment. He also quotes 
without comment tlse preceding partigraph, in which Sanders 
describes the ending of the fibre posteriorly, and, as above 
stilted, he dismisses Studnicka’s sttitements which confirmed 
those of Sanders, I'emarking that the appeartinces so inter- 
preted by Sludnicka must be due to the disturbed and 
abnormal condition of the fibre in his preparations. 
Sargent’s only other statement which bears upon the con- 
dition of the fibre in Myxinoids is tlie wholly unwarranted 
assumption (’04, p. 162) tliat “ In Myxine, wiiich is blind 
Reissner’s fibre must be made up wholly of axons 
from the olfactory centre in the ganglion habenulae.” 
the only instance in the vei'tebrate kingdom of the entire absence of an 
important section of the brain, viz. the cerebellum.” It was Sanders, 
too, w'ho first pointed out the existence of the terminal sinus in Myxine. 
Retzius to whom is commonly attributed the discovery of this terminal 
dilatation of the spinal cord, to which he gave the name of the terminal 
sinus, only published in the following year. Sanders’ descrijjtion of the 
condition of the hinder end of the canalis centralis of the spinal 
cord anticipated Sterzi's V>y more than a dozen years. 
