314 
SUM M ARY OF CURRENT RESEARCHES RELATING TO 
furrow extends from month to cloaca, and in this furrow lies the ex- 
tremely rudimentary foot. 
The skin includes a strong chitinons cuticle with spicules of lime, and 
a thin hypodermis with glandular prolongations which enter, but do not 
traverse the cuticle. Some of these glands form spicules. In regard 
to the musculature Hubrecht’s account is confirmed. The longitudinal 
fold which represents the foot is covered with ciliated epithelium ; on 
each side there is a glandular cushion which secretes slime, and is 
innervated from the pedal commissure ; there is no communication 
between ventral furrow and body-cavity. The author gives a useful 
tabular comparison of the nervous systems of Proneomenia, Dondersia , 
Neomenia , Lepidomenia , and Paramenia. In Proneomenia the anterior 
pleural ganglia are absent, and the pleural nerves arise directly from 
the brain. In regard to the vascular system, the author has certain cor- 
rections to make in Hubrecht’s description ; thus, the system is wholly 
lacunar. The heart remains in an embryonic state, consisting of an 
anterior and a posterior dorsal involution of the pericardium, and these 
pockets remain open above. Peculiar villi in the mouth, which Hubrecht 
was inclined to regard as respiratory, are without cilia, and are probably 
sensory palps. The histology of the entire gut is described. Finally, 
Herr Heuscher gives an account of the paired hermaphrodite gonad, 
the two ducts which lead from it into the pericardium, and the two 
“ nephridial ” canals which pass from the pericardium, and, uniting 
terminally, enter the cloaca. 
5. liamelli'brancliiata. 
Seat of Coloration in Green Oysters.* — M. J. Chatin finds that the 
most successful method of treating the gills of the Oyster is to use 
1 500 solution of osmic acid, absolute alcohol, aud safranin as a staining 
reagent. In pieces thus prepared it is easy to distinguish certain cells ; 
they are found almost exclusively in the apical region of the branchial 
papillae, where they are set with remarkable symmetry. These cells are 
of considerable size, regularly rounded ; they have a diameter of more 
than 250 ft, and they may be called macrobiasts. They are bounded by 
a protoplasmic layer so refractive as to resemble a cuticular membrane, 
though it is really a simple ectoplasm, principally formed of hyaloplasm. 
The chief part of the cell is formed by a very granular paraplasm, and 
the granulations, in Green Oysters, are coloured by a bluish pigment. 
These granulations are protoplasmic, and must not be considered as 
of nuclear origin ; the nucleus, in fresh cells, is almost always masked 
by the granulations. The cells one might be tempted to regard as 
symbiotic plant-cells, but they are not so ; they are really constituent 
elements of the tissues of the Mollusc, and they are also found in white 
or colourless Oysters, where they only differ in the want of the coloured 
granulations. 
Oysters from JJ.W. Coast of United States.f — Prof. E. C. Schiedt 
has discovered that, unlike other American Oysters, those from the coast 
of Oregon and Washington are, like Ostrea edulis of Europe, herma- 
* Comptes Rendus, cxvi. (1893) pp. 264-7. 
t I’roc. Acad. Nat. Sci. Philadelphia, 1892, pp. 351 and 2. 
