ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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sisted in mordanting the preparations for four hours in ferric alum 
2*5 grm., water 100 ccm., and then staining for 18 hours in ha3matoxylin 
0 • 5 grm., water 100 ccm. The preparations should be decolorised to the 
extent that the nucleus is quite black and the cytoplasm unstained. 
Black haematoxylin was also used for staining. Preparations stained 
with this fluid may be advantageously contrast-stained with crocein, or 
by decolorising with orange or carmin-blue. In fact the cytoplasm may 
bo completely decolorised with 0 • 1 grm. of carmin-blue dissolved in 
500 ccm. of alcohol at 80°. The preparations may be mounted in 
glycerin (50 per cent.) This fluid, while very suitable for examining 
the objects, is very detrimental to the stains, as the yeasts are more or 
less rapidly decolorised. The authors, after having examined and drawn 
the preparations, mount them in dammar-colophon (resin), after having 
contrast-stained them with Congo or Bordeaux red, crocein, or carmin- 
blue. 
The cover-glasses must not be warmed, or the yeasts will shrink to 
about half their former bulk. In connection with these preparations, 
the value of amylic alcohol is noted. After the preparations have been 
passed through a series of alcohols up to 95°, a drop of amylic alcohol is 
placed on the cover-glass. This fluid, being denser than ordinary alcohol, 
forms a layer immediately beneath the latter and above the specimens, 
and, though insoluble in water, is extremely effective in dehydrating the 
yeasts, and also in preventing their absorption of moisture. 
(3) Cutting 1 , including Imbedding and Microtomes. 
Imbedding and Staining Lichens.*— Mr. G. H. French recommends 
that lichens should first be immersed in 95 per cent, alcohol for 24 hours, 
and then placed in thin celloidin and thick celloidin for 24 hours 
each. The specimens are imbedded in thick celloidin, which is hard- 
ened in 70 per cent, alcohol for 24 hours, and then cut. Staining with 
borax-carmin gives the fungus part of the lichen a pale pink hue, while 
the algal cells have a greenish-red shade. In this way the host-cells 
are readily distinguished from the fungus. 
(4) Staining and Injecting. 
Methylen-Blue for Investigating Respiration in Plants.j — Prof. 
J. B. Farmer points out the usefulness of methylen-blue for demon- 
strating the reducing power of living protoplasm. If germinating 
seedlings of barley or peas be placed in a test-tube filled with a 
0 * 0005 per cent, solution of methylen-blue which has been boiled to 
expel the air, the liquid around them will in the course of a few hours 
be decolorised. If some of the decolorised fluid be withdrawn with a 
pipette and shaken up with air, the blue tint speedily returns. Still 
more striking results were obtained by putting CJiara cells in the dark 
in the methylen-blue solution. 
With many plants the reaction is tardy, and with all the result is 
attained more quickly if the plants have previously been starved of 
oxygen. It seems probable that the oxygen obtained by reducing the 
* Journ. Applied Microscopy, i. (1898) p. 135. 
f Nature, lviii. (1898) pp. 185-6. 
