ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
537 
the mercury changed into gold amalgam. Finally, black delicate designs 
appear on a white field. According to the thickness of the section, the 
fluid is allowed to act for 15 to 30 minutes, but even longer is not 
harmful. Thereupon the sections are quickly washed first in 50 per cent, 
alcohol, then in distilled water, and finally in a 10 per cent, solution of 
hyposulphite of soda, in which, according to their thickness, they remain 
for 5 to 10 minutes. A longer immersion bleaches too much, so that 
the finer fibres disappear. Last of all they are thoroughly washed in 
distilled water twice renewed. 
Sections thus fixed can afterwards be stained by any method— e.g. 
Weigert’s, Pal’s, &c. — after which they are cleared up with creosote, 
imbedded in dammar, and protected with a cover-glass. 
Throughout the procedure the sections must be manipulated with 
glass instruments, and not allowed to touch any metallic substance. 
Decalcification of Bone.* — In discussing various methods for decal- 
cifying bone, and after indicating the shortcomings of the different 
solutions, most of which have been in vogue for a long time, Dr. R. Haug 
points out the advantages of phloroglucin in combination with acid. 
The introduction of this reagent was due to J. Andeer, who used it with 
a solution of hydrochloric acid.f According to the author this method 
was not altogether satisfactory, since the results were not invariable. 
By substituting nitric acid for hydrochloric a decalcifying fluid is ob- 
tained which effects its purpose very rapidly. Days and hours are only 
required where formerly weeks and months were necessary, and this 
without any damage to the tissues generally. 
The solution is prepared by warming 1 grm. phloroglucin in 1 ccm. 
of pure non-fuming nitric acid (sp. gr. 1*4). This must be done slowly 
and very carefully, with slight agitation. After a very lively reaction a 
clear, dark ruby-red solution is obtained. To this combination of nitric 
acid and phloroglucin, which may be called nitrate of phloroglucin, 
50 ccm. of water are to be added. In order to obtain a sufficient quantity 
of decalcifying fluid, to this stock solution 50 ccm. of water and 10 ccm. 
of acid are again added, and further additions of like percentages of water 
and acid may be made until the quantity reaches 300 ccm., which is the 
limit of the protective influence of the phloroglucin. Of course, if a 
further quantity of the decalcifying fluid be required, a fresh stock of 
solution must be made, and so on. 
Foetal or young bones of lower Yertebrata are completely softened 
in half an hour ; older and harder bones, such as femur, temporal bone, 
&c., require a few hours. Of course, the pieces are small and the material 
previously washed. For teeth the amount of acid may be increased to 
35 per cent. 
When sufficiently decalcified, the preparations are to be placed in run- 
ning water for about two days, in order to thoroughly remove all traces 
of acid. The after-treatment is as usual. If a less rapid decalcification 
be desired, the following formula suffices to give very good results : — 
Phloroglucin, 1 ; nitric acid, 5; alcohol, 70; distilled water, 30. 
Other decalcifying methods are also discussed by the author; these 
* Zeitschr. f. Wiss. Mikr., viii. (1891) pp. 1-11. 
t See this Journal, 1887, p. 504. 
2 p 
1891. 
