828 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
alcoholic solution ; fixing by picric acid will improve the results. Adult 
Amphibia should be decalcified and fixed with chromic and nitric acids ; 
they should be stained with borax-carmine. 
Preparing Epithelium of Mid-gut of Arthropods.* * * § — Sig. 0. Visart 
opens the living animal, keeping it immersed in running water, and 
injects by the anus a concentrated solution of methyl-blue in alcohol 
at 80. The gut is then ligatured, and left for a quarter of an hour. On 
opening the gut, the epithelium is found completely separate from the 
tunica propria, and furnishes most satisfactory preparations. 
Mode of Preparing Crustacean Eyes.f— Mr. G. H. Parker states 
that most of his specimens were stained in Czokor’s alum-cochineal and 
mounted in benzol-balsam. The agent used in depigmenting sections 
was an aqueous solution (1/4 per cent.) of potassic hydrate. 
Preparing Segmental Organs of Hirudinea.J — Prof. H. Bolsius 
found the following combination useful ; after staining with haematoxylin 
the leech was washed for half an hour in a nearly concentrated solution 
of pure picric acid. By this double coloration the nucleus was stained 
by the haematoxylin, while the protoplasm of the segmental cells was 
yellow. This method introduces much variety into the coloration of 
the other tissues of the body. The muciparous cells are blue, the 
spermatozoa have cherry-red nuclei, the ova are rosy, the epithelial cells 
of the intestine violet-red with very deep nuclei, the ganglia are deep 
lilac, the nerve-chain almost black, the lymphatic and blood-cavities 
yellow to brown, the muscles are straw-coloured with red nuclei, and the 
connective tissue is of a clear yellow colour. 
Eismond’s Method of Studying living Infusoria. § — M. A. Certes 
reports that this method || gives excellent results. He has attempted to 
improve on it by the addition of colouring matters, and he has fully 
succeeded with methyl-blue and violet dahlia No. 170; with the latter 
the species studied did not live long ; with the other, survival is very 
much longer, unless the solution is too concentrated. 
Demonstration of Presence of Iron in Chromatin by Micro- 
chemical Methods.1T — Hr. A. B. Macallum states that he has discovered 
a method of employing ammonium sulphide as a reagent for iron, by 
which he is able to show the presence of the latter in the chromatin of 
the nuclei of a very large number of species of cells hardened in alcohol. 
The iron does not here occur combined as an albuminate, but rather in 
a condition comparable to the combination seen in potassium ferro- 
cyanide or haematin. Experiments with vegetable cells and such animal 
cells as those of the corneal epithelium of Amphibia show that the iron 
found is not due to the presence of haematin. Moreover, when chro- 
matin is very abundant the iron reaction is very marked, while it is 
feeble in cells poor in chromatin. In the chromatin loops and filaments 
of karyokinetic figures the iron reaction is intense and sharply confined 
* Atti Soc. Tosc. Sci. Nat., vii. (1891) pp. 277-85. 
f Bull. Mus. Comp. Zool., xxi. (1891) p. 141. 
} La Cellule, vii. (1891) pp. 5-6. 
§ Bull. Soc. Zool. France, xvi. (1891) pp. 93-4. 
H See this Journal, ante, p. 141. 
% Proc. Roy. Soc, Lond., xlix. (1891) pp. 48S-9. 
