4.60 BERTRAM H. WATERS. 
manner as that described by Orr for those of the medulla, or 
encephalomeres : 
(4) That all these segmentations, whether giving origin to 
nerves or not, rapidly and early degenerate. 
Since the preparation of this paper one has been published 
by Miss Platt (22) bearing upon the subject. She has de- 
veloped the relation of the neuromeres to the protovertebre, 
but falls into the error of confounding with the neuromeric 
segmentation, the so-called vesicular segmentation. She differs 
from Béraneck, Orr, McClure, and myself as to the relations 
of the nerves to their corresponding neuromeres, at least in 
the Chick, deriving them from the constrictions between, and 
not from the crests of, the neuromeres; and holds that the 
internal ridge described by Orr is composed of cells which 
converge to the root of origin of the nerve from that region. 
Hence she connects the latter with both the neuromeres 
between which it arises, and upon this ground assumes the 
individuality of the seventh and eighth nerves. 
I cannot agree with Miss Platt upon this point. I have 
never observed any such conditions even in very early stages 
of Chick embryos. From the fact that both McClure’s obser- 
vations and my own support the original statement of Orr 
concerning the point of nerve origin, I find her statements diffi- 
cult to accept. 
It will be seen that these investigations left the primitive 
condition of the fore-brain very doubtful and that of the mid- 
brain undetermined. I have attempted by the study of Fish 
and Amphibian embryos to confirm the points already made 
and to add some new ones, regarding especially the fore- and 
mid-brain. 
The investigations, of which this paper is a résumé, were 
undertaken during the winter of 1889-90 in the Morpho- 
logical Laboratory at Princeton under the direction of Dr. 
Henry F. Osborn, to whom I wish to express my deep obliga- 
tion, not only for the kindly interest which enabled me to 
complete the work, but also for many valuable suggestions. 
It was intended, by the study of some low form of Ichthyopsida, 
