ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
571 
structures that are distorted or obliterated by many other fixatives may 
be constantly and distinctly defined with cliromo-acetic. 
Preparation of Specimens of Spermatobium.* — Mr. G. Eisen, after 
trying a dozen or more stains, found the following method to be superior 
to any other, and to give by far the finest nuclear images : — (1) Staining 
of the hosts in toto — in very weak Delafield’s haematoxylin, or in Ehrlich’s 
ammonia-haematoxylin ; (2) hardening and sectioning in paraffin ; (3) the 
slide fixing consisted simply of distilled water, or of formalin and 
gelatin (one-half per cent, in water). This fixing is used as follows : — 
(1) Cover the space of the cover-glass on the slide with several drops of 
the fixing so that the sections will float ; (2) warm gently over a plate 
until the paraffin becomes slightly transparent, but not so long that it 
begins to melt ; (3) let the fixing harden in the air during at least four 
hours, or better, during the night. Sections treated in this way never 
loosen, and are always straight. They should never be melted, but the 
paraffin dissolved in pure turpentine or xylol. When the latter is at 
last removed, the slides are stained by a saturated solution of orange G 
in 33 per cent, alcohol. The stain should be left on only a few seconds, 
and then immediately washed off in 94 per cent, alcohol. If it is found 
that the nuclei of the hosts are not sufficiently brightly or too darkly 
stained by the haematoxylin, the slide may be again stained by a weak 
solution of Ehrlich’s ammonia-hrematoxylin under the Microscope. 
Then clear with oil of bergamot and mount in gum Thus ; in xylol such 
sections give exceedingly good images. The author calls attention to 
the very great advantages of gum Thus in xylol as a mounting medium, 
for it gives images far superior to those obtained with Canada balsam or 
dammar. 
Preparation of Nervous System of Cestodes. f — Mr. W. L. Tower 
found in his study of the nervous system of Cestodes that the Golgi and 
methylen-blue methods proved of very little value. He has, however, 
been more successful in the use of Yom Path’s killing fluid. The 
Cestodes examined were taken from the small intestine of the sheep 
twenty minutes after the sheep was killed, and placed in warm normal 
salt solution, in which they remained for 30 minutes. They were 
then put into the following mixture 500 ccm. sat. aq. sol. picric acid, 
filtered ; 3 ccm. glacial acetic acid ; 5 grm. platinic chloride in 5 ccm. 
dist. water ; 2 grm. osmic acid crystals. After being in this mixture 
for ten hours the worms were removed, and cut into pieces from 1 to 
3 cm. long. They were then put into fresh crude pyroligneous acid for 
6-10 hours, and then into 70 per cent, alcohol for a day. After de- 
hydration the pieces were soaked in xylol for 24 hours, and then im- 
bedded in paraffin. By this treatment nerve-tissue is differentiated from 
muscular and connective tissue, the nerves being coloured greyish-blue, 
whereas the more highly refractive muscles become brownish, and the 
connective tissue remains paler than either of the two other tissues. 
Method for Demonstrating Axis-Cylinders of Nerve-Pibres.l— Dr. 
R. Marcliesini recommends the following procedure for demonstrating 
axis-cylinders. The freshly removed sciatic nerve of a dog is placed at 
* Proc. California Acad. Sci., v. pp. 3-5. f Zool. Anzeig., xix. pp. 323-4. 
+ Anat. Anzeig., xii. (1896) pp. 211-5 (2 figs.). 
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