ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
155 
the suggestions of Greppin and Obregia in preserving the impregnated 
sections, for he has found that the chromate of silver deposit and the 
chloride of gold, while fixing the protoplasmic expansions and the large 
axis-cylinders, act very unfavourably on the delicate collateral branchlets, 
causing them sometimes to disappear altogether. 
Permanent Preparations of Aleurone and its inclosed Substances.* 
— Dr. F. Krasser recommends the following methods for the differentia- 
tion of the ground-substance, crystalloids, and globoids in aleurone 
grains. A very favourable object is Bicinus communis. 
1. Picrin-eosin. — Sections are fixed with picric acid dissolved in 
absolute alcohol, and the excess removed by absolute or very concen- 
trated alcohol, and are then stained by eosin dissolved in absolute 
alcohol, cleared by oil of cloves, and set up in Canada balsam dissolved 
in chloroform. The staining is accomplished in a very few minutes. 
The preparation shows the ground-substance dark-red, the crystalloid 
yellow with a sharp outline, the globoid nearly colourless or reddish. 
2. Picrin-nigrosin. — The section is placed in a saturated solution of 
picric acid in absolute alcohol, in which nigrosin has been dissolved to 
saturation ; the staining is continued until the ground-substance becomes 
blue. The preparation is then washed with absolute alcohol and placed 
for a very short time in oil of cloves, and set up in Canada balsam. 
The ground-substance is blue, the globoid colourless, the crystalloid 
yellow-green with a sharp outline. 
Very good preparations of the crystalloids alone can be obtained by 
staining with eosin after first dissolving off the ground-substance and 
globoids by a very dilute aqueous solution of sodium phosphate. 
“Microplyne” and “ Microzete.”f — M. L. G. Chauveaud describes 
two appliances which he finds of great use in the preparation and 
examination of sections of vegetable tissues. The “ microplyne ” is a 
small glass funnel with a delicate perforated disc of platinum placed 
across the tube. On this disc is first of all placed a layer of powdered 
glass ; then the sections of tissue which have been properly prepared, then 
another layer of powdered glass; and the staining reagent is then 
allowed to filter through the powdered glass on to the section ; the 
excess filtering away through the lower layer of glass. The watch- 
glasses containing the stained sections are then placed in the “ micro- 
zete,” a table illuminated from below by movable double black and 
white mirrors, and with a movable lens above by which to examine 
them. 
C4) Staining' and Injecting. 
Some Methods of treating hTerve-tissues.J — Dr. W. C. Krauss 
writes : — “ The aims to be sought after in the study of microscopy arc not 
alone those looking to the perfection of the instrument nor those which 
bear upon the selection of the specimen. The preparation of this 
specimen, and more especially the method of staining, is as important 
as the specimen itself. American microscopists arc more intent upon 
the former ; the European microscopists pay more attention to the latter. 
* S.B. K. K. Zool.-Bot. Gesell. Wien, May 29, 1891. See Bot. Centralbl., xlviii. 
(1891) p. 282. t Ann. Sci. Nat. (Bot.), xiv. (1891) pp. 16-24 (3 figs.). 
X Proc Amer. Soc. Micr., xii. (1891) pp. 116-9. 
