QUARTERLY CHRONICLE. 145 
the paper itself. (See ‘Kolliker und Siebold’s Zeitschrift,’ 
Jan., 1856.) 
The Egg-shells of Birds, from a Histological and Develop- 
mental Point of View, is the title of a valuable paper recently 
published by Dr. Hermann Landois. This distinguished 
microscopist describes, first, the general structure of the shell 
of birds’ eggs. He then gives details as regards no less than 
sixty-six species of birds, and afterwards enters into the ques- 
tion of the formation and growth of the egg-shell in the 
parent bird. In an appendix to the paper the eggs of two 
forms of reptiles are considered. Dr. Landois has made ex- 
tensive use of the nitrate of rosaniline in his researches, 
which promises to form a valuable aid to investigation in the 
hands of the microscopist. (See ‘ Kolliker und Siebold’s 
Zeitschrift, January, 1865.) 
Observations on the Structure of the Nervous Tissue by a 
New Method. By P. Roupanovsxy. (‘Comptes Rendus,’ 
Dec. 22, 1864.)—The method proposed and made use of by 
the author of this remarkably interesting paper is as follows: 
—lst. Prepare with a Valentin’s knife sections of the nervous 
tissue, frozen by a temperature of from 10 to 15 degrees 
Reaumur. 2nd. Colour them by means of infusion of cochi- 
neal or carmine. 8rd. Cover the pieces with Canada balsam, 
or with a special mixture composed of concentrated “ icthyo- 
colla,” six or seven parts, to eight parts of glycerine. The ob- 
servations made by M. Roudanovsky by means of this method 
are of great interest. With regard to the structure of the 
spinal nerves, he draws the following conclusions, the manipu- 
lation he adopts probably tending less to the distortion of 
structure than that used by other observers : 
lst. In examining a transverse section of one of these 
nerves one perceives that the primitive element of the nerves 
are tubes with a pentagonal or hexagonal configuration. 
2nd. The walls of the nerve-tubes formed by connecting 
tissue present in all cases, by their continuity, a veritable 
reticulum. 
3rd. The same tissue forming the walls of the tubes gives 
rise to, in some directions among the tubes themselves and 
among the bundles of tubes, cavities or reservoirs, by means of 
which the nutrient flinds are enabled to operate. 
4th. The isolated appearance of nervous tubes is an arti- 
ficial phenomenon. 
5th. The cylinders of the axes are coloured by the cochi- 
neal as well as the walls of the tubes; the cylinders of the 
axes appear in the centre of the tubes under the form of 
knotted fibres. 
