No. 3.] BUDDING IN PEROPHORA. ALI 
of his completed paper he published a preliminary note,! in 
which he stated that “when the differentiation of the ‘ endo- 
derm’ into the branchial and two peribranchial sacs takes 
place, it does so in such a way that the developing blastozodid 
is connected with the double-walled partition of the stolon, not 
by the branchial sac, as has been hitherto supposed, but by the 
left peribranchial sac’’; but no mention was made of the rotation 
of the vesicle by means of which this condition is brought 
about. 
Shortly afterwards, a brief account? of my results on P. viridis 
was published, in which I described the rotation of the inner 
vesicle and showed by means of figures that this process causes 
the septum of the stolon to become connected with the left 
peribranchial and not the branchial sac. I have repeated this 
statement, because from the account given by Ritter of the 
relation of the bud to the stolon (/oc. cz¢., pp. 190, 192) one would 
infer that all my observations were merely a confirmation of 
his, as he says, “Lefevre fully confirms my results in this 
particular’; whereas, before the appearance of my note, the 
above quotation, which affords no explanation of the process 
which brings about the connection of the septum with the left 
peribranchial sac, was the only published statement of his on 
the subject. 
I am fully aware of the danger of inferring that, because 
something takes place in a certain way in the bud development 
of one ascidian, the same is true of another, however closely the 
two forms may be related, and in the light of all we know con- 
cerning the budding of different ascidians it is not surprising 
to find even great differences. It is, therefore, perfectly pos- 
sible that both Ritter and myself are correct in our observations 
on the derivation of the pericardium and dorsal tube in the two 
species of Perophora which we have studied; and that in the 
one these organs are formed both by cells given off directly 
from the wall of the vesicle to their rudiments, and also by free 
cells of the blood, while in the other it is from this latter source 
alone that they arise. Ritter’s account, however, is not abso- 
1 Anat. Anz., Bd. x, No. 11. 
2 Johns Hopkins University Circulars, No. 119, June, 1895. 
