256 
PROGRESS OF MICROSCOPICAL SCIENCE. 
ance of tlie openings, the arrangement of spicules, and the formation 
of fibres. M. Barrois limits the term of oscules to the apertures of 
the cavities of the mesodermic system. They are homotypes of the 
pores. 
Histology of the Hctir. — Tliis subject has been recently worked at 
by Herr Ebner, who has presented a memoir upon it to the Viennese 
Academy of Sciences (July 12). Among other things he shows that 
the inner root sheath is essential for hair formation, and though 
broken through by the hair, it grows during the whole hair vege- 
tation, in the lower part of the follicle with even greater rapidity than 
the hair. He defends Langer's view that the new hairs are formed in 
the old follicle and on the old papilla, and describes fully the me- 
chanism of the progress. 
The Anatomy and Development of the Brain in Fish-lihe Verte- 
brates has been the subject of a recent communication to the Phila- 
delphia Academy, by Professor B. G. Wilder, of Cornel University. 
It is published as a brief Eeport in the ' American Naturalist ' for 
August, which states that after considering the taxonomic value of the 
brain, he spoke of the investigations of Huxley, Owen, and the conti- 
nental naturalists, dwelling particularly upon the causes of the great 
inaccuracy in the figures of fishes' brains contained in the text-books. 
He had endeavoured to ascertain how far the brains of fishes might be 
homologized with the typical brain described and figured in diagram 
by Huxley. The differentiation of the three typical cerebral vesicles 
was described, and the fact stated that while the typical description 
applies to all the higher vertebrate brains, neither the lateral ventricles 
nor the foramen of Munroe had been observed in the brains of fishes 
until recently found by Professor Wilder in the gar-pike. He had 
since found them in the lamprey and the hag-fish, in several sharks 
and skates, in sturgeons, in the spoon-bill sturgeon, in the mud-fish or 
Amia, and in several typical bony fishes. He showed in what way the 
nearly solid front mass of the adult shark's brain is formed from a 
thin- walled vesicle in the embryo. The structure of the brain in 
ganoids and teleosts was described, and the distinction indicated that 
in the latter, although the lateral ventricles and the foramen of Munroe 
are present, they are so small as to be almost invisible. We are forced 
back, therefore, in searching for the distinctive character of the ganoid 
brain, upon the chiasma of the optic nerves of Miiller. In considering 
the taxonomic value of these characters, the belief was expressed that 
the structure of brains will be found to be less dependent upon ex- 
ternal modifying circumstances than are other parts of the animal 
organization. In conclusion Professor Wilder exhibited and described 
the brain of Chimsera, and indicated its relations to the other groups 
spoken of. He regarded the brain as presenting characters inter- 
mediate between the sharks and skates, the ganoids and the batrachians 
with Lepidosteus. 
Botifers within Volvox. — This fact, which has been noticed over 
and over again, has a recent note upon it in ' Science Gossip ' for 
October. The writer, Mr. G. F. Chantrell, Hon. Secretary of the 
