102 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
30 minutes to 1 hour ; in the alcohols, 10 to 30 minutes, except in the 
absolute, which is 30 minutes to 1 hour. After the absolute alcohol 
the preparations are returned to 50° spirit. 
For staining, Bohmer’s hmmatoxylin w r as used. The preparaiions 
were immersed in a very dilute solution for 12-24 hours, and afterwards 
differentiated in 50° spirit faintly acidulated with hydrochloric acid. 
This treatment turns the colour red, but the blue hue is restored by 
washing in faintly ammoniacal 50° spirit. 
For certain details Heidenhain’s iron-alum haematoxylin is useful. 
The preparation may be contrast stained with eosin or with eosin and 
orange G. The preparations should remain in very weak solutions for 
3-12 hours. For pieces which have been treated with Flemming’s fluid, 
safranin is recommended. 
Lactic Acid in Botanical Microtechnique.* — Though lactic acid 
was introduced into botanical microtechnique quite ten years ago, says 
Herr F. Krasser, it has been but little employed. In the hot condition it 
was used as a solvent, in the cold as a fixative. With glycerin lastic 
acid has certain properties iu common ; it is of syrupy consistence, it is 
as clear as water, it is miscible with water and alcohol, it forms soluble 
salts, and has the property of extracting water. On the other hand, 
while it is miscible with ether, glycerin is not. It penetrates vegetable 
tissues more quickly than glycerin. Both are clarifying, and in both 
chloral hydrate can be dissolved for raising the refractive indices. At 
ordinary temperatures lactic acid causes but little swelling of vegetable 
membranes and starch-granules ; hence it is more suitable than glycerin 
and lactophenol for observing and preparing starch-granules and amy- 
laceous tissue. Next to starch it is of service for examining different 
kinds of flour. A small mass of flour may be mixed with acid and ex- 
amined directly, or the mass may be placed between cover-glass and 
slide and the acid allowed to run in. Tissues which contain aleuron- 
grains as well as starcli can be equally well examined and preserved in 
lactic acid. For tissues containing fat and a pigment it does not appear 
to be suitable. 
The chief value of lactic acid in microtechnique is as an observing 
reagent and preservative medium for starch, amylaceous tissue, and 
flour. 
Cover-glass Preparations of Amoebse.f — In order to obtain good 
preparations of amoeba, M. J. Tsujitani uses the following method. A 
droplet of distilled water is placed on a cover-glass, then a small quan-* 
tity of an amoeba culture, and lastly a loopful of a saturated solution of 
hydrochlorate of quinine. After they have been mixed and spread out, 
the layer is allowed to dry in the air, and is then fixed in the alcohol- 
ether mixture. The preparation is stained with metbylen-blue. 
Decolorising Algae. £ — Dr. H. C. Sorby has found that diluted 
formalin has a powerful action on the colouring matter of algae, and has 
succeeded in so reducing the colour of some very dark spines as to be 
* Zeitsclir. d. allgem. osterreich. Apotheker-Yereins, lii. (1898) No. 21. See 
Bot. Centralbl., lxxvii. (1898) pp. 89-90. 
f Centralbl. Bakt. u. Far., l ta Abt., xxiv. (1898) p. 670. 
X ‘ Floieamus ’ (Sheffield), 1898, No. 4, p. 68. 
