ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
897 
and projects half beyond it ; it is then lowered by the screw g until 
almost in contact with the blade. 
Thanhoffer Knife. — Fig. 110 represents a knife for Microscope sec- 
tions, which is provided with a water-spray. 
Preserving Fluids.* — Dr. F. Krasser recommends, as a highly anti- 
septic preserving fluid for vegetable preparations, a mixture of 1 vol. 
acetic acid, 3 vols. glycerin, and 10 vols. of an about 50 percent, solution 
of sodium chloride. It has also the property, in many cases, of preserv- 
ing the natural colour of the section. The author also refers to the 
property of a 1 per cent, alcoholic solution of salicyl-aldehyde of fixing 
the colour of pigments, as, e. g. that of the chromatophores of Solarium 
Ly coper sicum. 
(4) Staining- and Injecting. 
Methods of Staining Medullated Nerve-fibres. — The following is 
an account of the remarks made by Dr. Beevor at the meeting in 
October. Dr. C. E. Beevor, after stating that the title of his paper was 
not quite correct, as not only the fibres but the cells also were stained, 
briefly described the methods of work with the following stains : — 
Weigert's Acid Fuchsin Method . — The material is hardened in a 
3 per cent, solution of potassium bichromate for six weeks, then im- 
bedded in celloidin, cut, and the sections placed in a saturated aqueous 
solution of acid fuchsin. They are then washed in water, and trans- 
ferred to absolute alcohol with 1 per cent, of caustic potash until the 
grey matter is of a lighter colour than the white. The sections are 
again washed in water before mounting. This method may also be 
used for staining in toto, and afterwards imbedding in paraffin. 
Weigert's Hsematoxylin Method (1884). — The material is hardened 
for from two to six months in potassium bichromate, imbedded in celloi- 
din, sectioned, and transferred direct for 24 hours into a solution 
of hsematoxylin (haematoxylin 1 grm., absolute alcohol 10 ccm., water 
90 ccm.). The sections are then washed quickly in water, and passed 
into the following solution : — Ferricyanide of potash 2J- parts, borax 
2 parts, water 100 parts, in which they can be left until no more colour 
comes out. Afterwards wash in water, dehydrate in absolute alcohol, 
clear in oil of cloves, and mount in Canada balsam. 
The medullated fibres are stained dark blue, and the grey matter and 
fibrous tissue a pale yellow. 
Staining in toto with this method is not a success as the hasmatoxylin 
will not penetrate. 
Prof. Weigert recommends the addition of a minute quantity of an 
alkali such as lithia carbonate to the hasmatoxylin solution, which turns 
it a dark purple colour. 
Weigert's Copper Method (1885). — Weigert puts the imbedded block 
into a solution of acetate of copper half saturated, and then cuts, 
stains, and treats with the ferricyanide solution. 
Dr. Beevor said that he usually used this method after sectioning, 
placing the sections in a solution of acetate of copper, washing off the 
excess in methylated alcohol, then staining and developing. 
* SB. K. K. Zool.-Bot. Gesell. Wien, xlii. (1892) p. 56. 
