No.1.] BUDDING IN GOODSIRIA AND PEROPHORA. 163 
4. DEVELOPMENT OF THE UNDIFFERENTIATED Bup. 
The earliest stage which I have observed in the development 
of a bud is represented by Fig. 11, Pl. XII. Here the bud Axlage 
is clearly marked, dd¢.a., both by the character of the cells and 
by the slight evagination already seen. But as yet the ecto- 
derm shows no indication of having been affected by the 
process which has begun in the wall of the peribranchial sac 
beneath it. It is true its cells are higher immediately over 
the evagination than they are at any point more ventralward ; 
but they are not higher than they are from this point upward 
toward the dorsal side of the zooid, as the figure shows. 
That is to say, the ectoderm cells are not different over the 
bud from what they are in a corresponding position of a zooid 
in which no bud is developing. 
The figure shows approximately the stage of development of 
the parent zooid. The endostyle, ezd., is not yet fully differen- 
tiated, histologically, and the thickened places, s¢.a., in the wall 
of the peribranchial sac opposite the bud show where branchial 
stigmata are going to form. The string of cells, ev.c., near the 
bud, is a fragment of one of the ‘“endocarps”’ that has been 
broken and displaced somewhat in the section cutting. It 
consequently has no significance. 
To the important question of whether the bud Ax/age arises 
from a “budding zone” on the peribranchial wall in which 
the cells are “embryonal,” and are endowed from their very 
origin with peculiar bud-producing powers, my observations do 
not enable me to give a wholly satisfactory answer. However, 
certain facts are suggestive in this connection. I have never 
found anything that appears like a “ budding zone”’ similar to 
that described by Oka, for example, in Botryllus, and I find 
that the walls of the peribranchial sacs in the developing bud 
are, after the very first stages of their growth, very thin through- 
out, the cells being considerably flattened. Their development 
is, of necessity, accompanied by cell division, but I am unable 
to discover that this is more noticeable in one region than in 
another; or that the cells have a different appearance or 
distribution in one locality from what they have in another. 
