730 SUMMAEY or CURRENT KESEA.RCHES RELATING TO 



reagents, in water, to wliicli alcoliol or a fe^v drops of acid have been 

 added. Small animals, and embryos of higher animals, esi^ecially 

 those which have not a strong external skeleton, are put alive into a 

 1/8-1/2 per cent, solution of chromic acid till they are dead, then 

 treated with several drops of concentrated chromic acid, and finally 

 washed, first in 30 per cent, alcohol, and then in gradually increasing 

 strength up to absolute. 



As staining reagents, borax- carmine, ammonia-carmine, and log- 

 wood are used. 



By starving or exposing to a low temperature the lower animals, 

 insects, worms, &c.. Brass has discovered that the granular substance 

 inside the cells is dissolved and reabsorbed, and that finally the 

 nuclear corpuscles disappear by degrees. 



To study this process in the higher Yertebrata — parrots, mice, 

 rabbits, &c. — they were infected with tuberculosis. The chromatic 

 substance of the cells disappeared more or less, especially in those 

 of the ovum, in which the changes were very marked, as ascertained 

 from sections of the ovary. 



Demonstrating the Nuclei in Blood-corpuscles.* — Herr M. 

 Ladowsky recommends for the demonstration of the nuclei in white 

 blood-corpuscles treatment with solutions of osmic acid (1 per cent.), or 

 ^eak solutions of picric or chromic acid, and subsequent staining with 

 rosanilin, saftranin, or better methylen- green. The latter is also 

 useful for demonstrating the stroma and nucleus of red corpuscles. 

 The author shows that the white corpuscles are not sticky by inject- 

 ing watery solutions of indigo-blue, eosin, or even distilled water 

 into the blood, which make the plasma cells aggregate in heaps, 

 whereas the white corpuscles circulate unchanged. 



Demonstration of Karyokinesis in Epithelial Tissues.t— Signer 

 Tizzoni employs the method of fixing the tissue with Mliller's fluid, 

 hardening, preserving in ordinary alcohol, and staining with alum- 

 carmine, which diflerentiates the chromatic figures of cell-nuclei in a 

 state of division with the same distinctness as logwood and safiranin ; 

 the resting nuclei assume a violet colour, those which are dividing a 

 ruby-red colour. This diflerence of staining points to a difference in 

 chemical composition. The alum-carmine which the author uses is 

 made by adding to Grenacher's formula a trace of sodium sulphate, 

 which increases its staining power. 



Investigating the Structure of the Central Nervous Organs.! — 

 Dr. J. Stilling recommends that pieces of brain hardened in 

 chromium salts should be placed, after washing, in red or rectified 

 pyroxylic acid or artificial pyroxylic acid (glac. acet. ac. 100 g. ; 

 ordinary water 800 g. ; kreasote 30 minims). The connective 

 tissue swells, and is quite macerated, so that the nerve-fibres, which 

 remain intact, can be prepared under water with needles and forceps. 

 The specimens can afterwards be stained with picro-carmine. 



* Virchow's Arch. f. Path. Ai;at., xcvi. (ISSi) pp. 60-100. 



t Bull. Sci. Med. Boloc^na, 1SS4, p. 259. 



i Zeitsclir. f. Wiss. Mikr.. i. (1SS4; pp. 5S6-7. 



