40 BULLETIN OF THE 
cells in the lateral bud and the very early completion of its commu- 
nication plate, the immediate needs of the polypide, which arises only 
after the formation of the plate, being met by this supply of stored 
nutriment.! 
But why is the septum (communication plate) formed so early, if it 
is desirable for the species that the growing tip should be well nourished 
by the fluids of the body cavity? Here again I must resort to pure 
hypothesis. I assume that the early formation of the septum is a pro- 
vision for the protection of the stock against a rapid influx of the sur- 
rounding water in case the brauch is broken, One can understand how, 
if the body wall and growing regions depend upon the fluids of the body 
cavity for nutrition, an open communication of this cavity with the out- 
side world would be a serious obstacle to regeneration of the body wall in 
the lost part, or the growth of the stock in any other direction. There is 
a fact which ought to be mentioned in this connection, as bearing on this 
hypothesis of the function of the septa. One frequently finds that in 
stocks which have been handled with reasonable care the median branches 
are broken off at either end, and in almost every colony one or more lat- 
eral branches are missing from the parent branch. Apparently, then, 
the lateral branches are unusually subject to destruction, and we find 
the septs developed at a much earlier period between them and the an- 
cestral branch than between individuals of the median branch. Compare 
Plate IT. Figure 14, in which the communication plate has not yet begun 
to form, with Plate VI. Figure 58. 
III. Budding in Marine Gymnolsmata. 
1, ARCHITECTURE OF THE STOCK. 
T have already described the process of stock-building in Paludicella, 
and have attempted to show that it follows a certain law. I desire now 
to present a few observations upon the architecture of certain stocks of 
marine Gymnolsemata, which will aid in arriving at some general con- 
clusions later on. Other observers have worked out the architectural 
laws of single species or groups, and I shall refer to their studies either 
1 Similar conditions to those in Palndicella exist in some marine Bryozoa, and in 
one of these cases, Bowerbankia, I find them fulfilled by a similar arrangement. The 
young buds of the stolon which give rise to the “nutritive zodids” are, at an early 
stage, loaded with food granules, As in Paludicella, so in Bowerbankia the 
communication plates are formed early. 
