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SUMMARY OF CURRENT RESEARCHES RELATING TO 
which is connected anteriorly and posteriorly with the pericardiac wall, 
and remains open so as to allow of a communication between the lumen 
of the heart and the coelom. The cardiac tube becomes very early 
constricted in its middle, the auricle appearing in the anterior and the 
ventricle in the posterior half. The blood-vessels are formed from 
lacunar spaces of the coelom, which are inclosed by mesoderm cells. 
They soon become connected with the heart. All the ganglia are 
formed by delamination from the ectoderm, and arise independently of 
one another. The ventral ganglia appear in the velar area under the 
rudiments of the tentacles, and the buccal ganglia from the ectoderm of 
the oesophagus. The intestinal ganglia are formed on either side of 
the middle of the body, but are soon twisted, one above and the other 
below the intestine. The visceral ganglion is developed in the ecto- 
derm of the pallial cavity. 
The primitive kidney is formed on either side from a mass of 
mesoderm cells in which a cavity soon appears. The saccules grow out 
into a tube, one end of which reaches to the surface and breaks through 
the ectoderm. The opposite end becomes ciliated internally, but it is 
not certain that it has an internal orifice. 
Anatomy of Corambe testudinaria.* — M. H. Fischer gives an ac- 
count of the anatomy of this recently described species of Nudibranch. 
On account of the peculiarities which it presents, the author thinks it is 
more nearly allied to the Anthobranchiata than to the Polybranchiata ; 
it has, however, some resemblances to the Phyllidiidm. 
The embryo, at the moment of extrusion, has the pigmented body 
which has been described in Philine as the anal eye. 
Hepatic Epithelium of Testacella.f — M. J. Chatin has studied the 
minute anatomy of the so-called liver of Testacella haliotidea. He finds 
that the tubes of this organ are lined by large, depressed cells, inter- 
mediate in form between the cubical and the pavement cells. They vary 
in size, and have no proper membrane ; a slight differentiation of the 
protoplasm can just be made out at their periphery. The protoplasm 
itself is reticulated and spongy, and between the bars there is a less 
refractive fluid substance in which there are granulations. Some of 
these last are brilliant and colourless, while others are yellowish or 
brownish. 
Among these cells there are others which are smaller, have a large 
nucleus, and an almost homogeneous protoplasm ; these appear to be 
young cells, ready to replace the older ones. 
Intermediate stages can be made out between the flattened cells of 
the caeca, and the elongated cells of the canals of which the organ is com- 
posed ; and this gland in Testacella may be cited as one which offers every 
intermediate stage between mosaic and palisade epithelium, which are 
usually regarded as profoundly different. The author concludes by 
insisting on the value of researches in Zoological Histology. 
Heart of Dentalium.J — Dr. L. Plate finds that Lacaze-Duthiers was 
in error in denying the existence of a heart in Dentalium. It is present, 
* Comptes Rendus, cxii. (1891) pp. 504-7. 
X Zool. Anzeig., xiv. (1891) pp. 78-80. 
t T. c,, pp. 493-4. 
