ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 713 



After the acetic acid process, the covers are immersed in the gentian 

 violet solution for a few seconds only, then washed carefully in water, 

 and finally mounted in xylol halsara. 



Staining Capsule-Cocci.* — The difficulty experienced in staining 

 capsule-cocci arises from the fact that the ground-substance of the 

 preparation is so deeply coloured tbat the enveloping capsule is 

 invisible, although the cocci can be discerned. 



This difficulty Dr. C. Friedliinder points out may be obviated by 

 first passing the preparation thrice through the flame of a spirit-lamp, 

 aud then immersing for one or more minutes in one per cent, acetic 

 acid. The superfluous acid fluid is blown by means of a pipette, and 

 the preparation dried in the air is placed in the gentian violet solu- 

 tion (100 cc. anilin water, 11 cc. saturated alcoholic solution of 

 gentian violet) for a few seconds, washed with water, and examined. 

 By this process the ground-substance remains colourless, while the 

 capsules, if any, stand out quite prominently. By cautious treatment 

 with weak acetic acid or alcohol, the characteristic form of the sphaaro- 

 bacteria sometimes appears, for the staining of the capsules is less 

 resistant to both of these reagents than that of the bacteria them- 

 ' selves. In the majority of recent cases of fibrinous pneumonia, capsule- 

 cocci can be found in the manner above indicated, but within the 

 pneumonic exudation otber Micrococci forms appear, chiefly Diplo- 

 cocci. These forms may be distinguished from capsule-bacteria both 

 by the want of capsule and also by their smaller dimensions. 



After - Staining by the Haidenhain Method.-]"— Prof. W. 

 Flemming states tbat preparations made by this method may be 

 much improved by after-staining with Grenadier's alum-carmine or 

 with Delafield's or Bbhmer's hematoxylin. The blackened pieces, as 

 small as possible, are after being washed in water to be immersed 

 in the stain for two or three days, and then before cutting are to be 

 further hardened for some hours in absolute alcohol. Sections of 

 mucin glands stained with hematoxylin show a beautiful violet 

 colour on these cells. It may be remarked that for successful staining 

 the blackening should not be too intense. 



Nuclear Stain in Osmic Acid Preparations. $ — The objection is 

 often raised that hardening in pure osmic acid is an impediment to 

 good staining. This inconvenience Prof. W. Flemming finds may 

 be obviated by an after treatment with bichromate of potash, when 

 a good stain is effected by means of Bohmer's or Delafield's haema- 

 toxylin. After treatment with bichromate is, however, unnecessary 

 if the osmic acid preparations are not kept too long in alcohol, and 

 have not become too much darkened. They are best stained before 

 they are transferred to alcohol. Alum-carmine also gives a good 

 stain with osmic acid preparations in twelve to twenty-four hours. 

 The author uses a 1 or 2 per cent, watery solution (not the 

 vapour) of osmic acid, and hardens in the dark for about six hours, 

 and mounts in glycerin. 



* Fortschr. d. Medicin, iii. (1885) p. 380. 



t Zeitsckr. f. Wiss. Mikr., ii. (1S85) pp. 517-8. J Ibid., pp. 518-9. 



