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MISCELLANEOUS. 
On the Anatomy and Histology of Branchiostoma lubricum, Costa 
(Amphioxus lanceolatus, Yarrell). By M. J. Marcusen, of 
St. Petersburg. 
Ir might be thought that, after the investigations of Johannes 
Miller and Quatrefages, there would be little to discover in the ana- 
tomy and histology of this curious animal. But as it is now nearly 
twenty years since these naturalists published their memoirs, and as 
since that time the means of research have been greatly improved, 
during my residence at Naples I submitted the Branchiostoma to a 
new examination, which has led me to the discovery of many facts 
unknown to my predecessors, and enabled me to rectify several of 
their results. 
VERTEBRAL SYSTEM. 
1. Dorsal Chord.—This is composed, as is well known, of a sheath 
and contents. The latter were described by Goodsir and Muller as 
consisting of a fibrous mass separable into disks. Quatrefages has 
denied the existence of the latter, and declared that the dorsal chord 
is composed of juxtaposed cells, of which he has given figures. 
According to my investigations, the cells do not exist; and Max 
Schultze has also been unable to discover them. The dorsal chord 
separates so readily into disks that they may be recognized even in 
the living animal, but the separation is not complete. The disks are 
very thin, their thickness being only 545th mill., and they are 
wnited on the two sides by a very delicate substance, whicn issues 
from the two surfaces at a great many points, so that in separating 
one disk from its neighbour the uniting membrane is torn, and its 
débris present a net-like appearance upon the surface of the disk, 
giving the latter an aspect of being composed of cells. In reality, 
however, there is only a smooth disk, of which the surface is covered 
with shreds of the uniting substance. Sometimes we may see in the 
substance of the disk itself several perfectly transparent nuclei. 
Perhaps the network of the uniting substance may represent the 
remains of cells; but otherwise there are no cells in the dorsal chord 
of the Branchiostoma. 
2. Buecal Cartilage.—This cartilage, as well as its processes 
which form the skeleton of the buccal cirri, is also composed of a 
mass which separates readily into disks ; but here the cells of which 
these are composed have not entirely disappeared, for nuclei of larger 
or smaller size are seen granulated into an intercellular mass. 
-Quatrefages saw this; but he believed he saw cells without nuclei, 
with their outlines contiguous—which do not occur. 
NERVOUS SYSTEM. 
Quatrefages has the credit of having described the distribution of 
the nerves better than his predecessors; and it is also to him that 
“we owe the interesting observation that the central nervous system 
‘is composed of a series of inflations corresponding with the origin of 
