108 BULLETIN OF THE 
rial before the formation of the communication plate, and yield it up to 
the rapidly growing bud. 
The regenerated polypides, like the marginal ones, arise in Choilo- 
stomes in a definite position, —on the wall of the operculum from tissue 
left behind to give rise to the polypide, but not wholly used up in its 
formation. They arise wholly from the body wall, come to lie next to 
the “ brown body,” and cause its disintegration. 
The more important theoretical conclusions to which I have arrived 
are :— 
a. There is in every stock or corm of Bryozoa a mass of indifferent 
cell material, which is derived directly from the indifferent cells of the 
larva or embryo, and whose function is to form the organs of the different 
individuals, including the polypides. This mass by constant growth and 
division affords the embryonic material for lateral branches, 
d. The form of the stock and interrelation of individuals is in large 
part controlled by food supply. 
c. The inner layer of the Phylactolamatous larva represents meso- 
derm only: the entoderm has become rudimentary through loss of the 
alimentary function. 
d. The polypides arise in Phylactolamata at the pole of ingression, 
which is probably homologous with the aboral pole of Gymnolemata, 
e. The inner layer of the polypide bud is composed of cells derived 
from the rim of the blastopore, and they are to be regarded as still 
indifferent, and as first becoming differentiated into ectoderm and ento- 
derm in the formation of the young polypide. 
f. Gemmiparous tissue is a rapidly assimilating tissue possessing 
large nuclei because actively assimilating, and staining deeply because 
full of food material. 
g. The Endoproct and Ectoproct larvae are to be compared by assum- 
ing that the act of rotation of the axes occurring in the former has been 
leaped over in the ontogeny, the mouth and anus arising at once on the 
pole opposite the blastopore. 
CAMBRIDGE, Mass., June 1, 1891. 
