214 Mr. G. Lefevre on 
The material at my disposal, which had been prepared in 
various ways, proved to be most excellent for my purpose, as 
it contained unlimited numbers of buds in every stage of 
development. 
I might mention here that I have made use of Patten’s 
method of orientation to much advantage, and have found it 
of invaluable assistance in manipulating the very small young 
buds ; in this way I was enabled to cut sections with great 
accuracy in any plane desired. 
I was soon led to believe that in the early development of 
the buds Perophora presents novel and interesting features ; 
moreover, some of the results arrived at are at variance with 
those which have been obtained by previous workers on this 
and other Ascidians. 
The very young bud consists of two vesicles, one within 
the other, which enclose between them many free mesen- 
chyme-cells. The outer one is derived directly from the 
stolonic ectoderm, while the double-walled partition of the 
stolon gives rise to the inner or endodermal vesicie. 
This partition, which is made up of flat cells, is continuous 
throughout the entire length of the stolon as a double-walled 
plate which divides the stolon in half longitudinally and ex- 
tends from one side to the other. 
The buds always arise in the plane of the stolonic partition, 
but may appear on either side of the stolon. When the 
ectodermal wall of the stolon begins to push out to form the 
ectoderm of the bud, the free border of the partition evaginates 
at this point to give rise to the endodermal vesicle of the bud. 
The bud-rudiment lies at first almost at right angles to the 
long axis, but soon becomes inclined towards the free tip of 
the stolon, the inclination being due to an elongation in this 
direction. Instead of having a spherical shape, as at first, 
the bud-rudiment now assumes the form of an ellipsoid. By 
this process of growth the connexion with the stolon comes to 
be placed at the posterior portion of the bud, while the ante- 
rior end lies free along the surface of thestolon. ‘The anterior 
end is therefore directed towards the free growing tip of the 
stolon ; the side next the stolonic wall is the ventral surface, 
and that turned away from it is the dorsal. 
If a transverse section of a bud, when it consists merely of 
two simple concentric vesicles, be examined, it will be found 
that the wall of the endodermal vesicle is thicker on the right 
side than elsewhere. In such a section, which is represented 
in fig. 1, the ectoderm of the stolon is seen to be continuous 
with that of the bud-rudiment, and the connexion of the inner 
vesicle with the stolonic partition is clearly shown. 
