1070 SUMMARY OF CURRENT RESEARCHES RELATING TO 



nucloin within tho nucleus ; it leavos tho membrane, the karyoplasma, 

 and the plasmatic nucleoli unstained ; whereas carmine, logwood, 

 anilin violet, safranin, &c, are only uncertain reagents, for these stain 

 all nuclear elements indifferently, tho plasmatic nucleoli, perhaps, 

 even more intensely than the nuclcin. Tho solvent used for tho 

 albuminoids, as vitellin and myosin, were ' 001 per cent, hydro- 

 chloric acid, and ' 1 per cent, salt solution. The micro-chemical 

 characters of nuclein given arc : the nuclein substances are almost 

 insoluble in water, insoluble in dilute mineral acids (partially soluble 

 in strong acids), but easily soluble in very dilute alkalies. In a 

 solution of sea-salt they swell up, forming a gelatinous mass. They 

 present, with iodine, nitric acid, and Millon's reagent, the reactions 

 of the protein substances. All these properties enable the nuclein 

 substances to be easily distinguished from lecithin and albuminoids. 

 It is, perhaps, owing to the nuclein that nuclei stain with picrocarmine. 

 For the study of the polar globules, fresh and preserved material 

 was employed. (1) A small piece of an ovary was placed in a drop of 

 methyl-green on a slide. The egg was then fixed (a) with 3 per cent, 

 nitric acid, 50 and 70 per cent, alcohol, after Van Beneden's metbod. 

 Instead of leaving the eggs two hours in 50 per cent, alcohol in order 

 to obtain karyokinetic figures, the author merely washed with 

 50 per cent, alcohol until all the acid was removed, and then treated 

 with 70 per cent, alcohol ; (b) with absolute alcohol, to which a 

 quantity of sulphuric acid was added. A large drop of this spirit is 

 then run over the eggs on the slide until the methyl-green is quite 

 decolorized ; then the acid is carefully washed away ; next glycerin or 

 Ripart's fluid plus a little glycerin is added to the preparation. 

 (2) For fixing and hardening ovaries intended for later use, these 

 were treated (a) with 3 per cent, nitric acid ; (b) with sulphuric acid 

 alcohol, in which the objects are left for one to eight hours, according 

 to the thickness of their membrane ; after having been well soaked the 

 objects are transferred to strong spirit ; (c) The solution of mercury 

 perchloride according to Gilson's formula may be used. The ovaries 

 remain herein for 20 minutes to an hour, are then well washed in 

 water and preserved in alcohol. In any case the eggs are stained 

 with metbyl-green. Of all the reagents sulphuric acid alcohol gave 

 the best results. 



Preparing Spermatozoa.* — For making permanent preparations 

 of spermatozoa Sir. A. C. Cole says that no method succeeds better 

 than receiving the perfectly fresh 6eminal fluid into a watchglass 

 containing glycerin diluted with its own bulk of water, and a single 

 drop of osmic acid solution. After mixing gently by means of a 

 needle, drops of this fluid may be taken up by means of a pipette, 

 deposited on slides, covered, and secured with gold size. By this 

 method spermatozoa are mounted in a fluid of about the same refrac- 

 tive power as the natural seminal fluid, and appear as in life. Tbe 

 whole cell is preserved unaltered, except that its contour is slightly 

 sharpened and the nucleus brought into greater prominence. 



* Cole's ' Studies in Microscopical Science,' iv. (1886), Sec. 2, p. 6. 



