162 RITTER. [Vou. XII. 
Figs. 37 and 38, Pl. XV, taken from two different zooids, 
represent the points at which the vessels open into the body 
space of the zooids. I would call particular attention to 
Fig. 37, since this illustrates a much more common appearance 
than that shown in Fig. 38. The projections, ec.ves', into the 
cavity I understand to be due to the vessel’s having pushed 
itself therein, either by its own growth or by its passive resist- 
ance to the expansion of the developing zooid. In many cases 
it appears that the wall of the zooid has been pushed in toa 
considerable extent by the vessel ; and by an interfolding of the 
vessel wall and the zooid wall, the character of the connection 
has become quite complicated. In some instances these pro- 
jections extend entirely across the body space to the wall of 
the peribranchial sac. 
I said above that it 1s almost certain that these communica- 
tions are secondary. ‘This qualification was made because one 
might ask if the vessels do not sprout out from each of the 
blastozooids, as it would seem they must have done from the 
sexually produced ancestor of the colony. 
That this process never occurs I cannot positively affirm, 
but I have no evidence that it does, and two considerations 
incline me to the belief that it does not. In the first place, 
the peculiar character of the connection, as described and 
shown in Fig. 37, seems to me to speak against such a process ; 
and in the second place, one would suppose that if it takes 
place at all it would do so at a rather early stage in the devel- 
opment of the zooid, before the ectodermal cells in the region 
from which the vessels would have to be produced had undergone 
modification. But I have searched in vain for cases of such 
formation. 
By carefully examining all the sections of numerous buds at 
various stages in development, one can determine that there 
are no connections whatever between them and the vessels. 
This is the fact that makes me believe that the connection of 
the buds to the vessels is not essential to the development and 
life of the zooids. 

