ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
487 
Simple Method for Demonstrating the Production of Gas by Bac- 
teria.* — Mr. H. E. Durham describes a modification of the fermentation 
tube which consists in placing a small test-tube in an inverted position 
within the ordinary test-tube used for cultivations. The small tube 
should be freely movable when placed inside. The tubes are filled by 
means of a burette, and are then steam sterilised on 
three successive days. In most cases the smaller tube Fig. 95. 
becomes completely filled after the first sterilisation, and 
it is not usual for a bubble to persist after the second. 
The tubes must not be tilted too much when they are 
inoculated (fig. 95). 
Demonstrating Pacini’s Corpuscles.^ — Pacini’s cor- 
puscles, which may be regarded as the highest develop- 
ment of nerve-endings, are easily demonstrable by intra 
vitam staining. The animal is to be injected with a 
saturated solution of methylen-blue at 37°, and when 
dead the pieces are to be stained in saturated aqueous 
solution of picrate of ammonia. Methylen-blue forms 
with picrate of ammonia a combination insoluble in 
water, but soluble in spirit. The preparations are then 
immersed in a solution of molybdate of ammonia 1, 
water 20, aceto-hydrochloric acid 1 drop. With molyb- 
dic acid, methylen-blue forms a compound insoluble in 
alcohol, and now the preparations can be dehydrated, 
imbedded, cut, stained, and mounted without detriment. 
Formol-Methylen-Blue Treatment of Nerve-fibres4 
— Herren G. Eossolino and W. Muraview adopt the 
following procedure for the demonstration of normal or 
diseased nerve-fibres. The pieces are placed for one or 
two days in 2-2*5 per cent, formalin, and then trans- 
ferred finally to 4 per cent, formalin. After at least 
four days the formalin may be exchanged for 95 per cent, 
alcohol, and the pieces teased out or sectioned. The 
pieces or sections are stained in a hot 0 * 5 per cent, aqueous methylen- 
blue solution. After the solution has cooled down, the preparations 
are transferred to 1 per cent, alcoholic solution of anilin for a few 
seconds or for some minutes. They are then washed in 95 per cent, 
alcohol to remove the anilin, cleared up in cajeput oil, and mounted 
in balsam. 
By this procedure two different kinds of nerve-fibres can be distin- 
guished. In one of these the medullary sheath is studded all over with 
small round granules of variable size and form. The method is satis- 
factory also for the nerve-cells and the connective tissue elements. The 
preparations are permanent, retaining the stain well, but they do not 
bear exposure to sunlight. 
Demonstrating the Nucleoli of Cells in Central Nervous Sys- 
tem.§ — Herr Y. Euzicka reports a method for demonstrating the histo- 
* Brit. Med. Journ., 1898, i. p. 1387 (1 fig.). 
f Zeitschr. f. angew. Mikr., iv. (1898) pp. 38-41. 
X Neurol. Centralbl., xvi. (1897) pp. 722-7. 
§ Zeitschr. f. wiss. Mikr., xiv. (1898) pp. 452-5. 
