ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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of Golgi’s silver method the observance of definite lengths of time for the 
different stages of the procedure is important. In frog’s brain the best 
results were obtained by allowing the hardening and impregnating 
fluids to act for twenty-four hours. For the brain of the triton and 
salamander twenty -four hours were sufficient. If the fluids were allowed 
to act for thirty to forty hours, the results were very unsatisfactory. 
Staining Medullary Sheath of Nerves of Spinal Cord and of 
Medulla. 3 " — Dr. A. Mercier says the following simple procedures give 
satisfactory results for sections of spinal cord and medulla. The sec- 
tions, according as they contain much or little of the chromic acid salt, 
are immersed in one of the two following solutions: — 
Solution 1. Weak alcohol, 100 ; haematox., 2 ; aq. dest., 100 ; alum, 2 ; 
glycerin, 100. 
Solution 2. Strong alcohol, 120 ; haematox., 2 ; aq. dest., 130 ; 
alum, 2 ; glycerin, 50. Dissolve the haematoxylin in spirit and the 
alum in the water, add to the latter the glycerin, and then mix with the 
haematoxylin in spirit. 
Herein the section remains from twelve to twenty-four hours. It is 
then washed carefully in water, after which it is transferred to a modi- 
fied Weigert’s decolorizer: — Aq. dest., 200; ferricyanide of potash, 6; 
borax, 4. When sufficiently decolorized it is washed in distilled water, 
dehydrated, cleared up in oil of clove, and mounted in balsam. 
It was found, however, that if the first decolorizing solution were 
followed by a second composed of potash, 10 per cent., 2 ccm. ; aq. dest., 
10 ccm. ; aether sulphureus, 1 ccm., the differentiation was more satis- 
factory. 
Demonstrating Nerve-end Plates in Tendons of Vertebrata.f — Sig. 
G. V. Ciaccio adopted the following method for demonstrating nerve- 
endings in tendons of Amphibia. The pieces were taken from a living 
animal, or from one just dead, and placed at once in 1/1000 hydrochloric 
acid, or better in 1/500 acetic acid until they were quite transparent. 
They were then immersed for five minutes in a mixture of gold 
chloride and potassium chloride solutions (1/1000 each). 
This imparts a pale yellow colour. 
The pieces were next placed in a large quantity of 1/500 acetic acid 
and kept there in the dark for a whole day, and then exposed to the 
sun for two or three hours. When the tendon has assumed a pale 
violet hue, it is taken out and placed for a day in 1/1000 osmic acid 
solution and finally mounted in glycerin to which 0 * 5 per cent, of its 
bulk of acetic or formic acid has been added. The medullated fibres 
are stained dark violet, their extreme terminations being also violet, but 
passing into red or blue. The tendon itself is stained a pale yellow or 
light violet. 
Preparing and Staining Testicle.J— Sig. H. Brazzola in studying 
the testicle and the formation of spermatozoa, found that Podwyssozki’s 
* Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 480-3. 
f Memorie R. Accad. Sci. Bologna, x. (1890) pp. 301-424 (6 pis.). See Zeitschr. 
f. Wiss. Mikr., vii. (1891) pp. 507-8. 
X Memorie R. Accad. Sci. Bologna, viii. (1888) pp. 681-94 (1 pi.); ix. (1888) 
pp. 79-85 (1 pi.). See Zeitschr. f. Wiss. Mikr., vii. (1891) pp. 516 -7. 
