518 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Tissues hardened in alcohol or in corrosive sublimate and spirit 

 stain more rapidly than those hardened in Midler's fluid or chromic 

 acid. In any case in which a fluid other than alcohol has been 

 used for hardening, the reagent must be entirely removed by immersion 

 in spirit. The length of time required for staining can only be learnt 

 by experience, but over-staining need not be feared. When the paraffin 

 or celloidin methods arc used, the best way is to immerse the slide, to 

 which the section is stuck on in a wide-mouthed vossel filled with stain. 

 Both stains give excellent results in photomicrography by lamplight, 

 owing to the sharp nuclear definition and slight staining of the other 

 tissue elements. 



Preparing Picrocarmine.* — The following, according to the ' Maga- 

 zino of Pharmacy,' is an improved method of preparing picrocarmine for 

 microscopical purposes : — 



About half a gramme of carmine is dissolved in 100 ccm. of water 

 containing 5 ccm. of a 1 per cent, solution of soda. The liquid is then 

 boiled, filtered, and made up again to 100 ccm. by addition of distilled 

 water. In order to neutralize the solution, it is mixed with an equal 

 volume of water, and a 1 per cent, solution of picric acid is then added. 

 This at first causes a turbidity to appear, but it subsequently disappears. 

 If not, it indicates that the point of neutralization has been overstepped. 



Staining with Rosanilin Nitrate in watery Glycerin Solution-! — 

 Dr. W. Flemming states that Bottcker has for a long time stained 

 preparations previously treated with Midler's fluid and alcohol with 

 rosanilin nitrate in a watery glycerin solution ; then passed through 

 alcohol, cleared up in creosote, and mounted in dammar or balsam. 



New Injecting Mass.J — Dr- M. N. Miller has devised the following 

 injecting mass : — 



First procure some thin, clear, colourless French gelatin in sheets 

 about 3 in. by 8 in., with crossed markings. To 1 oz. of gelatin add 

 10 oz. of water. Allow the gelatin to swell for one hour, and then 

 place the vessel containing the whole in a kettle of boiling water, and 

 allow it to remain until the gelatin melts thoroughly. Strain through 

 previously moistened flannel into, preferably, a flask. While yet warm 

 and fluid, pour about half of the gelatin into another glass vessel. Dis- 

 solve in the one half two grains of dry common salt, and in the other 

 half ten grains of nitrate of silver. Should the gelatin become stiffened 

 by cooling, it must be warmed and so kept fluid. When all is dissolved, 

 mix the two gelatin solutions and shake briskly for from three to five 

 minutes. Add 10 grains of citric acid and keep the gelatin warm until 

 the former dissolves. This is the injecting mass, and is ready for use. 

 If filtered first through paper the solution will be clearer, but this is 

 not absolutely essential. 



The colour of the injection mass in the mounted section is a beautiful 

 purple, and perfectly translucent. The differentiation between arterioles, 

 venules, and capillaries is perfect, and the larger the vessel, the darker 

 the colour of the mass. The citric acid must be put in last, and metal 

 vessels must not be used, as the silver salt would act upon them. The 

 mass is not spoilt if partly darkened before use. 



* Scientif. News, i. (1888) p. 319. 



t Arch. f. Mikr. Anat., xxx. (1887). 



$ Amer. Mori. Micr, Jouru., ix. (1888) pp. 50-1. 



