86 BULLETIN OF THE 
towards the side opposite the place of entrance, as the fibres one after 
another effected a union with the basal ends of the retinal cells. But 
nothing of the kind seems to exist in either of the cases cited or in those 
which have come under my own observation. The fibres, instead of 
following the surface of the bulb beneath the post-retinal membrane 
(‘‘ sclera”), traverse directly the retinal layer in several groups.* Their 
connection with the retinal cells, however, is not —as one would fairly 
infer from Grenacher’s account — at the posterior (ariginally free) ends, but 
rather with the anterior parts of the cells, t+—at least it may be designated 
as certainly pre-nuclear.{ The evidence of this rests partly upon the 
position and general direction of the nerve-strands in a region behind 
the forming bacilli and in front of the nuclei, and partly on the modifi- 
cation of form which many of the retinal cells and their nuclei exhibit 
in consequence of this relation. The elongation of the azterior ends of 
the nuclei § is so evidently a result of the peculiar position and connec- 
tions of the nerve-filaments (Pl. V, Figs. 23, 24) that I cannot for a 
moment think it attributable to any other cause. 
There is also reason to believe that a similar condition exists in the 
eyes of the “ post-nuclear” type, and that the nerve-fibres which appear 
to emerge from the deep surface of the retinal layer really pass around 
the margins of the tapetum (somewhat as in Pecten), to join the now super- 
jicial ends of the retinal cells. This in turn increases the probability of 
the znversion of the retina in “ post-nuclear” eyes. (Compare Explanation 
of Figures.) 
I shall return to a consideration of the manner in which this interest- 
ing connection is brought about in the pre-nuclear eyes, and of the prob- 
* Since the groups do not necessarily lie in the plane of the section, they are not 
all seen in one section ; but I am satisfied, from the examination of several cases, that 
such a division of the fibres usually takes place. 
+ That such a method of nerve-connection with sensory cells is not wholly with- 
out parallel, will be evident upon comparing the conditions here described with the 
account of the termination of the radial nerve of the cochlea in mammals as given 
by Lavdowsky (76, pp. 529, 530, Taf. 35, Figg. 10 A, 10 C). 
+ The connection here (after inversion) called ‘‘ pre-nuclear” is of course equiva- 
lent to a post-nuclear connection before inversion. The nerve-fibre, which I believe 
reaches the nucleus itself, therefore retains as nearly as possible its original method 
of connection with the retinal cells ; 7. e., it approaches the nucleus from what was 
originally the deep end of the hypodermal cell. 
§ The nuclei present no such modification of form in the earlier stages of the 
formation of the eye, before the appearance of the optic nerve, but are similarly 
rounded at both ends. 
