ZOOLOGY AND BOTANY, MICR03C0PY, ETC. 
83 
which would work effectively without ice-cooling, and be conveniently 
transformable into a combination not readily soluble. This was found 
in the ammonium-picrate combination recommended by Smirnow and 
Dogiel, which is almost insoluble in water, but readily soluble in alcohol. 
By subsequent treatment with ammonium molybdate or the like, the 
pigment becomes a molybdate salt. To attain this transformation six 
different methods, each with its particular merits and demerits, are 
suggested. 
Differentiating Nucleolar Structures.* * * § — Dr. Th. List distinguishes 
the main nucleolus, the accessory nucleolus, and the nucleolus pure and 
simple. The first is probably composed of nuclein, the other two are 
modifications of paranuclein. To produce in the section a Berlin blue 
staining of the accessory nucleoli, a reaction is effected between hydro- 
chloric acid and potassium ferro-cyanide. Or, if the sections be left 
half an hour in weak iron chloride solution acidified with hydrochloric 
(50 ccm. distilled water, 10 drops *5 per cent, iron chloride, 5-15 drops 
1 per cent, hydrochloric), the Berlin blue reaction is effected ; nuclein 
and the related substances remain colourless, the paranuclein of the ac- 
cessory nucleolus becomes blue. The same method is also useful for 
mucin-glands. 
Nerve-endings of Duck’s Bill.f — Dr. L. Szymonowicz fixed duck- 
embryos with osmic acid or with a mixture of cone, aqueous solution of 
picric acid (250 ccm.), cone, sublimate solution (250 ccm.), distilled 
water (500 ccm.), and glacial acetic acid (12 ccm.). For adult speci- 
mens he tried many fixatives, e.g. 12 parts cone, sublimate solution, 
and 2 parts of 2 per cent, osmic acid, Flemming’s and Hermann’s fluid, 
&c. He stained with Heidenhain’s iron-alum lisematoxylin and Weigert’s 
fibrin-colouring method. For differentiating the nerves he got best 
results with Ranvier’s gold-method (8 parts 1 per cent, gold chloride 
solution -f- 2 parts formic acid after heating). For the embryos he 
used the methylen-blue method. 
Weigert’s Neuroglia Method.;— Dr. B. Pollack calls attention to 
the importance of Weigert’s painstaking work § on the human neuroglia 
and on the methods therein expounded. Golgi’s method is applicable to 
animals almost exclusively, and especially to embryos ; Weigert’s method 
is applicable to man. Golgi’s method colours only some cells ; Weigert’s 
colours all nuclei and fibres. Golgi’s method yields a silhouette ; Wei- 
gert’s shows the natural form and size. Golgi’s method distinguishes 
only cells with processes ; Weigert’s method shows cell-body or nucleus 
differentiated from the processes. Golgi’s method colours besides the 
neuroglia the nervous tissue ; Weigert’s method differentiates the neu- 
roglia — a fact which in part explains how Golgi, Cajal, and most 
anatomists hold the neuroglia to be nervous, which Weigert, like 
Ranvier, vigorously denies. 
* MT. z. Stat. Neapel, xii. (1896) pp. 477-93 (1 pi.). 
f Arch. f. Mikr. Anat., xlviii. (1896) pp. 329-58 (1 pi.). 
t Tom. cit., pp. 274-80. 
§ ‘Beitrage zur Ivenntniss der normalen Mtnschlichen Neuroglia,’ Frankfurt 
a. M., 1895. 
