ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
707 
mother are different, for in Pedicellina the dorsal side of the bud is 
turned towards the ventral, and not, as in Loxosoma , to the dorsal side of 
the mouth. The most striking difference lies in the fact that the buds 
of Loxosoma become set free from the mother and form new points of 
attachment, while in Pedicellina they remain permanently connected 
with the parent, and a new colony can only be formed from a larva. 
The possession of a pedal gland by the buds of Loxosoma is another 
point by which this form can be distinguished from Pedicellina. 
In his study of the gymnolasmatous forms, Herr Seeliger has investi- 
gated especially Bugula avicularia, while B. flabellata , Membranipora 
pilosa, and Eucratsea Lafontii (?) have also been used. The process of 
budding is described as being very simple. The ectoderm and meso- 
derm give rise to the bud ; from the outer layer is formed the body- 
wall of the bud; and, as in the embryonic development from the blastula, 
the polypide is formed by a gastrula-like invagination. The latter gives 
rise to the tentacular sheath, the outer walls of the tentacles, and the 
digestive tract with all its parts. The basal portion of the invagination 
is constricted off from the proximal, and at only two points does connec- 
tion obtain ; these become the mouth and anus. While the basal part 
is divided into the several sections of the enteron. the tentacles rise up 
from the anterior part. These are at first arranged bilaterally, and are 
set in the form of a horse-shoe ; it is only later on that they form a 
closed circle. 
The mesoderm of the mother is partly arranged around the polypide 
invagination in the form of a unilaminate epithelium, while other mesen- 
chymatous cells remain scattered in the primitive body-cavity. The 
mesodermal epithelium gives rise to the tissue which fills the tentacular 
cavities, and the fine flattened epithelium which forms a peritoneal cover- 
ing to the enteric canal as far as the base of the tentacles. The author 
has not followed out the fate of the free mesoderm-cells ; it is possible 
that they give rise to the various muscular bands which traverse the 
body-cavity, and to the gonads. 
Dr. Seeliger points out the close agreement that exists between the 
mode of development of the ento- and ectoproctous Bryozoa ; the sole 
important difference lies in the relations of the mesoderm, but this is 
due to the differences in its structure. In the Entoprocta the separate 
mesenchyme-cells pass into the primary body-cavity of the bud, where 
they divide, and, during life, have the form of a connective tissue with- 
out ever becoming arranged in epithelial lamellse. In the GymnolaBmata, 
among the Ectoprocta, the enteric canal has, in its developed stage, a 
mesodermal epithelial investment, while a similar, at least complete, 
layer is always absent from the body-wall. For the rest, the body- 
cavity is, as in the Entoprocta, traversed by connective tissue and other 
mesodermal organs. The large muscular bands which arise from the 
mesenchyme have exactly the histological characters ascribed by the 
Hertwigs to the mesoblast-musculature. In the Phylactolsemata there 
is not only an epithelial mesoderm-layer around the enteron, but one 
lies against the ectoderm, so that the body-cavity is truly an enterocoel. 
With regard to the character of the mesoderm in the adult, the three 
groups of Bryozoa form a continuous series. In the Entoprocta a 
connective-tissue-like mesenchyme lies in the primary body-cavity ; in 
