No.1.] BUDDING IN GOODSIRIA AND PEROPHORA. 181 
representing sections of the ganglion well toward its posterior 
end show it apparently in organic connection with the ecto- 
derm. Their most pronounced statement concerning its origin 
which I can find is the following, occurring on page 311: 
“Dans les dernieres coupes il n’est pas possible dé voir la 
limite entre l’ébauche neurale et l’épiderme; elle parait étre 
un simple épaississement de |’épiblaste (Fig. 10, 11, et 12).” 
The authors’ conclusions certainly need confirmation before 
they are entitled to unqualified acceptance. 
The ectodermal origin of the ganglion asserted by Salensky 
and Brooks for Pyrosoma and Salpa, respectively, appears to 
be well supported in both cases, though it does not stand 
unchallenged, Seeliger ('89) claiming a mesodermal origin for 
it in both these genera. I have had no opportunity for personal 
observations on the point, and consequently shall express no 
opinion upon it further than this, that to my thinking even 
Pyrosoma is sufficiently remote in its relationship to the com- 
pound Ascidians to make possible an ectodermal origin of the 
ganglion in its ascidiozooids, while the same organ arises from 
the endoderm in the buds of the compound Ascidians. Seeing, 
as we do, the central nervous system arising from the ectoderm 
in the embryozootds, and from the “endoderm” in the blasto- 
zootds of the same species, its origin from either of these 
sources, or even from the mesoderm, in Pyvosoma, or still more 
in Sal/pa, ought not to cause great astonishment. That, how- 
ever, there are such radical differences within the same genus 
as results indicate cannot be accepted till more evidence is at 
hand than we yet have. 
The last-mentioned source of the ganglion, z.e. from the 
inner or ‘“endodermic”’ vesicle, was asserted by several inves- 
tigators whose observations were made a number of years ago, 
before the exacter methods of section-making had come into 
use in morphology, and before morphology had gone so greatly 
under bondage to the germ-layer theory as it has done more 
recently. And so it happened, as is not unfrequently the case 
in science, that the greater intellectual freedom enjoyed by 
the earlier workers more than offsets their cruder technique, 
and they were enabled to reach conclusions more nearly true 
