562 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
raised by 0*001 mm. and upwards. The instrument is provided with 
an adjustable snap-arrangement to enable any given thickness of section , 
within certain limits, to be obtained. It also possesses a clamp by 
which the knife may be adjusted square for the production of series of 
sections. 
C4) Staining- and Injecting-. 
Double-Staining for Distinguishing Living and Dead Substances 
after their Preservation.* — Dr. L. Rhumbler recommends a mixture of 
50 parts of a 1 per cent, watery solution of methyl-green, 50 parts 
of a solution of 0*8 grm. eosin in 50 per cent, alcohol, and 50 parts of 
absolute alcohol. With material preserved in picro-sulphuric acid or 
alcohol the stain acts, on sections and small pieces, in half an hour. After 
washing with water the material should be placed in alcohol of increasing 
strengths. Clearing and imbedding materials may be used as desired. 
This mixture has the property of staining brilliant red all the sub- 
stances which were alive when the material was preserved, while all 
dead organic or inorganic substances are stained bright green. In other 
words, the eosin acts on living substances as though there were no methyl- 
green in the mixture, and methyl-green acts as if there were no eosin. 
Organic substances which were beginning to break up at the time of 
preservation, or which consist of a mixture of organic and inorganic 
masses, as well as most of the secreted products of protoplasm, such as 
certain cell-membranes, the fresh secreted cementing substances of Rhi- 
zopod shells, and glandular secretions take both stains, and are reddisli- 
violet, violet, blue or blueisli-green, according to the proportion of dead 
or living material. The author recommends the mixture for the study 
of small organisms, especially Protozoa. 
It is particularly useful for finding minute organic bodies in mud 
or masses of detritus ; it is hardly possible to imagine a greater contrast 
than there is between the small living things and their surroundings. 
It is good also for distinguishing ingested food particles from other proto- 
plasmic constituents in the bodies of Protozoa, The method is said 
to afford an absolutely certain means of distinguishing between living 
and dead substances, and it gives a good clue as to the age of secreted 
substances. 
The author concludes with notes on some of his results, a fuller 
account of which will be given when he deals separately with the organ- 
isms investigated. 
Staining of Protoplasts and Cell-wall. f — Herr J. af Klercker recom- 
mends the following process for the staining of protoplasts in microtome- 
material. If the object examined is an aerial part of a plant, the oily 
substances are first removed by ether or dilute ammonia, and, after 
washing out the fixing material, the object is allowed somewhat to dry 
in order to promote the entrance of the staining substance. But if it is 
only the membrane which is to be stained, the object is brought, directly 
or after washing out the fixing material, into eau de Javelle or eau de 
Labarracque, and left there till all the protoplasm is dissolved. After 
* Zool. Anzeig., xvi. (1893) pp. 47, 57-G2. 
t Verb and 1. Biol. Yer, Stockholm, iv. (1892) No. 14, 4 pp. See Bot. Centralbl, 
liv. (1893) p. 41. 
