OBSERVATIONS ON THE CRANIAL NERVES OF SCYLLIUM. 483 
attachment. ‘Towards the close of stage k, the tertiary or anterior 
roots have appeared, arising almost certainly as outgrowths of 
the ganglion towards the brain ; but whether these are altogether 
new developments or merely new attachments of the primary 
root is uncertain. The seventh nerve (fig. 3) is in the same 
condition as the fifth at the preceding stage; it is now attached 
by both primary and secondary roots, the former, owing to 
the growth of the brain-roof, being widely separate from one 
another. 
At stage N the condition of the roots is much the same as at 
the end of stage xk. The fifth nerve (figs. 5 and 11) is attached 
by its secondary and tertiary roots, the latter being very con- 
stantly two in number, of which the anterior is the larger and 
attached to the brain some distance in front of the seeondary 
root (v 8). The seventh nerve (figs. 6, 11 and 12) is attached 
by both primary and secondary roots, the nerve between the 
two being in contact, but not in connection with the brain; the 
secondary root (fig. 11) is divided into an anterior or facial, and 
a posterior or auditory division. 
At stage o (figs. 8 and 9) the chief differences are—first, 
that, owing to increased growth of the brain, the distance 
between the primary and secondary roots of the seventh nerve is 
much greater than before; secondly, that the roots of the fifth 
and seventh nerves, which, from the first, have been quite inde- 
pendent of one another, are now situated much closer together 
than they were at the earlier stages. 
At stage o-p (fig. 14) the two roots of the seventh (vi1a and 
vit (3) are still further apart from one another, but are now very 
close to those of the fifth. The connection between the two 
nerves which we have already seen is fully established at stage x, 
and which is shown at stage Lin fig. 10 (N.c’.) and at stage n in 
fig. 11 (N.c’.), is, by stage o-P, very much more extensive and 
intimate than previously. The roots of the nerves are still quite 
distinct from one another (fig. 14), but immediately beyond 
these roots the two nerves become so closely and extensively 
united together that it is impossible to draw a line of separation 
between them. ‘The connection is rendered still more intimate 
by the crossing of one of the branches of the seventh, as will be 
described fully later on, over the main stem of the fifth, so as to 
lie in front of the branches of this nerve. 
The condition of the roots, as of the branches, of the fifth and 
seventh nerves at stage o-P differs but little from that of the adult, 
the sole change of importance as concerns the roots being that 
the ventral roots (v 8 and vir 3) approach still closer together, 
and come into actual contact. 
The primitive distinctness, gradual approximation, and ulti- 
