ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
439 
If the sections are to be arranged in “ series,” they are simply placed 
upon a slide one after the other, care being taken not to flood the slide 
with oil but to keep it quite dry. After the sections are arranged, the 
slide is tilted up to allow the excess of oil to drain away, fifteen minutes 
generally being sufficient. Balsam is now placed on the sections and a 
warm cover is allowed to gently fall over the series, no section of which 
ought to leave its place. 
The above method is especially useful in the preparation of larger 
yolk-bearing eggs. 
(4) Staining and Injecting. 
New Method for staining Central Nervous System.* — The pieces 
of nervous tissue are, says M. Lichen, to be placed for five weeks in a 
mixture of equal parts of 1 per cent, chloride of gold and 1 per cent, 
corrosive sublimate. The pieces are then sectioned in dilute lugol 
solution (1/4). 
The medullated or non-medullated fibres, the nerve-cells, and the 
neuroglia-cells are coloured blue. In the ganglion-cells nucleus and 
nucleolus were clearly differentiated. 
Methods of staining the Axis-cylinder in Sections of Spinal Cord.f 
— For staining spinal cord Herr Schmaus adopts the following modifi- 
cation of Gierke’s method : — 1 grin, of carminate of soda, 1/2 grm. of 
nitrate of uranium, and 100 grm. of water are heated for half an hour 
and filtered when cold. The sections are placed for 15 to 20 minutes in 
the staining fluid and then washed with water. 
The tissue must have been previously hardened in Muller’s fluid. 
By this method the axis-cylinders are perfectly stained while the 
celloidin is unaffected. 
In another method employed by Kronthal, carmine is used with 
great success. A saturated solution of carmine is made in ammonia, 
and the solution, merely covered with a piece of tracing paper, is allowed 
to stand for a week. The supernatant fluid is then decanted to a well- 
stoppered bottle and left for four weeks. 
In a mixture of 10 drops of this fluid and 100 ccm. of distilled water 
the sections are placed for 24 hours, after which they are washed with 
water for 24 hours. The older the solution is the greater its staining 
power, due to the formation of the carbonate of carmine, becomes. It 
does not stain the celloidin. 
A third method recommended by Schmaus is to stain the axis- 
cyliuders with English blue-black. The solution consists of 1/4 per 
cent, blue-black to 50 per cent, spirit with a little jficric acid added. 
After an immersion of one hour the sections are washed and mounted. 
Examination of Nerve-centres by Iodide of Palladium Process.^: — 
Prof. G. Paladino states that his process of studying the central nervous 
system consists in impregnation by chloride of palladium in a 1 per 1000 
solution, and formation of iodide of palladium by the reaction of iodide 
* Neurol. Ceutrdbl., 1891, No. 3. See Bull. Soc. Beige de Microscopie, xliii. 
(1891) p. 13. 
t Mimchener Med. Wochenscbr., 1891, No. 8. See Bull. Soc. Beige de Micro- 
scopie, xviii. (1891) pp. 11-12. 
\ Journ. de Micrograph ie, vi. (1892) pp. 77-8 
