ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
317 
Organization of Sinistral Prosobranchiate Gastropoda."*" — MM. P. 
Fiscber and E. L. Bouvier have examined some of these “ left-handed ” 
Mollnscs. In Neptunea contraria it was found that all the organs which 
are placed on the right in dextral Prosobranchs are on the left, and vice 
versa ; correlated modifications were observed in the organization of the 
animal, in, for example, the ganglia and the nerve-branches. 
Molluscoida. 
B. Bryozoa. 
Bryozoa of Japan. f — Dr. A. Ortmann has a paper on the Bryozoa 
collected by Dr. L. Doderlein in Japan, a region from which only three 
species were previously known. Of the 137 species reported on, 85 are 
said to be new, and three of these require new genera to be established 
for their reception. 
Asexual Multiplication of Endoproctal Polyzoa.J — Dr. 0. Seeliger 
has investigated the formation of the Polyzoon stock, the budding at the 
free end of the main stolon, the branching of the stolon, the forma- 
tion of new buds between the old, and finally the regeneration of the 
polype head. His general conclusions may be summed up as follows 
As in other classes, the budding process is condensed in contrast with 
the ordinary development. In Loxosoma the buds go free ; in Pedicellina 
they are fixed and become mature at their points of origin; in all cases 
they grow without metamorphosis, and exhibit none of the provisional 
larval structures. In the bud there is no process comparable to 
segmentation, for it starts as a two-layered rudiment, with epithelial 
ectoderm and with mesenchyme, but with the development of the inner 
layer much belated. In every forming bud, the ‘-polypide” originates 
from a fresh invagination of ectoderm, which is probably, to begin with, 
referable to a single cell. If this fact be connected with Nitsche’s 
observation that the mesenchyme in Loxosoma was derived from the 
ectoderm, then 0. Schmidt’s paradox about the buds of Loxosoma 
becomes intelligible — that the process is not a budding, but the direct 
development of an ovum which has passed into the ectoderm, and there 
starts the apparent bud. Neither Nitsche’s observation nor Schmidt’s 
conclusion is, however, to be accepted. According to Seeliger, the 
budding is a process of gastrulations repeated by the ectoderm on various 
regions of the adult animal or of its stolon. 
At the apex of the stolon, where large ectodermic cells lie, an 
evagination occurs which begins a bud. At the apex of this, the ecto- 
derm is invaginated to form the “ polypide.” A few mesoderm cells of 
the stolon have wandered into the cavity of the bud, where they multiply 
so rapidly as to fill the space. The polypide invagination is divided 
into two regions, an upper one which never loses its connection with the 
ectoderm layer, and a lower one which remains connected with the latter 
by a narrowing aperture which becomes the mouth. The upper part 
represents the atrium, and from it the tentacles arise with immigrant 
mesenchyme cells. By an evagination of the atrial wall the ganglion is 
* Comptes Rendus, cx. (J890) pp. 412-4. 
t Arch. f. Naturg., Ivi. (1890) pp. 1-74 (4 pis.). 
X Zeitschr. f. Wiss. Zool., xlix. (1889) pp. 168-208 (2 pis,, 6 figs.). 
