ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
711 
The object-holder li allows of the object being shifted horizontally. 
It consists of two metal plates, the upper one of which is movable in the 
vertical direction and can be fixed by two screws. Between these plates, 
therefore, the wooden block i on which the celloidin block is fastened 
can be adjusted in the horizontal direction and fixed. 
With an inclination of the knife-edge to the horizontal of 60° which 
is sufficient for sections 50 /x thick, the size of the sections can with this 
instrument amount to 2* * * § 5 X 2*5 cm. ; but for thinner sections of 15 to 
10 [x the inclination of the knife must be increased to 80°, and in this 
case the maximum size of the sections is only 1x2-5 cm. 
C4) Staining- and Injecting-. 
Nature of the Staining Process.*" — Herr G. Spohn has attempted to 
solve the question whether the colouring of cellulose-fibres by staining 
reagents depends on a chemical or on a mechanical combination. Micro- 
scopical examination of cotton-wool stained by mineral pigments showed 
no change whatever in the structure of the fibre itself. Even when the 
fibres were macerated before staining with alizarin, they acted simply as 
a carrier of the pigment, on which the macerating fluid acts chemically. 
In all cases the combination of the fibre and the pigment depends entirely 
on mechanical causes. 
New Process of Double-staining Vegetable Membranes, f — M. C. 
Roulet describes a method of double-staining by the successive use of 
cyanin and Congo-red. The sections are first decolorized by eau-de- 
Javelle, and then left for a quarter of an hour in a concentrated alcoholic 
solution of cyanin, then washed with absolute alcohol, and placed for a 
quarter of an hour in a 5 per cent, ammoniacal solution of Congo-red. 
After washing in alcohol, and mounting in xylol-Canada-balsam, the sec- 
tions present a magnificent double staining, the lignified membranes are 
coloured an intense blue, the cellulose-membranes rose-coloured or red. 
Staining living Sex-cells.J — Hr. M. Waldner, having observed that 
the spermatozoids of Marchantia survived staining with a weak solution 
of eosin-red, treated the spermatozoa of the trout in the same way. They 
took on the stain, remained active for fifteen minutes, and were able to 
fertilize ova. The egg-membrane resisted the stain, so that ova simi- 
larly treated remained colourless. 
Demonstrating Malaria Parasites.§ — M. A. Laveran spreads thin 
layers of blood on cover-glasses after the manner in which a layer of 
sputum is obtained. The blood-films are then dried in the air, and 
afterwards passed thrice through the flame of a spirit-lamp. The pre- 
parations are then mounted as they are, that is in air or dry, and the 
edge of the cover-glass just ringed round with paraffin to keep out dust 
and moisture. The films may be stained with an aqueous solution of 
methylen-blue for 30 seconds. After this they were washed rapidly in 
distilled water, dried, and mounted dry. The parasites are stained, but 
much paler than the nuclei of the leucocytes; the red corpuscles are 
unaffected. 
* Dingler’s Polytechnisch. Journ., cclxxxvii. (1893) Heft 9. See Bot. Centralbl., 
liv. (1893) p. 293. t Arch. Sci. Phys. et Nat,, xxix. (1893) p. 100. 
X Anat. Anzeig., viii. (1893) pp. 564-5. 
§ Trans. Seventh Internat. Congress Hygiene, ii. (1892) pp. 12-13. 
