Ill' Till-: A Mi; UK AN MONTHLY [April, 



MI( HOS(Ori( AL M VMPl LATION. 



Preparing and Staining Yeast. — Dr. II. Mocller used for 

 tixin>; \(.ast picpiiialions a i per cent, solution of iotliile of potas- 

 sium saturated \\ itli iodine, this lUiid ten times diluted, and al.so 

 ioiline-\\ ater. The ^material and the fixative may he mixed to- 

 gether at once or upon the cover-j^lass, w hieh merely reipiires a 

 smear. When fixed and dried the preparation must hethorouj^hlv 

 liardened. This may he done hy leavinj; the preparations in 

 the iodine solution tor a day. and then, after washing in water 

 anil weak spirit, keeping them in ahsolute alcohol tor one or two 

 days. The time rcipiired for hardening may be diminished by 

 repeatedly boiling the alcohol, and the preparations are more 

 clearly stained if they arc thenjimmcrsed in chloroform for a day. 

 It is always useful to pass the cover-glasses once or twice through 

 the flame. 



riie preparations are best stained 1)\- means of hu'inatein and 

 picric acid, the latter acting as a mordant. But it is essential 

 that the preparation should be thoroughly fixed and hardened : 

 they may then be treated with a saturated atjueous solution of 

 picric acitl for ^-3 hours ; the prejiaration is then passed through 

 water so as to wasii^ofV some, but not all. of the picric acid. For 

 staining, an alkaline .solution of h;i?matoxvlin is used. It would 

 not appear, however, that the foregoing staining was more ad- 

 vantageous than that with aniline, of which the following were 

 successfully employed : phenolfuchsin, alkaline methylen-blue, 

 Gram's method, and alsoj.gentian-violet in carbolic aciil, water, 

 glycerin, i per cent, acetic acid, and i per cent, iodide of potash. 



If the aniline dyes are used the preparation should be over 

 stained and then dilVerentiated by some decolorant ; if Gram's 

 metlKjd be adojjted alcohol must be used ; but for other stains a 

 mixture of equal volumes of glycerin and water was found to give 

 the best results. As soon as the desired degree of decolorization 

 is attained the preparation is washed in water, dried in the air, 

 and mounted in balsam, styrax, or dammar. 



The grana or microsomes were best brought out l)y staining 

 with some aniline dye anil then difi'ercntiating with 2 per cent, 

 acetic acid. 



.Spores are very easily stained by treating the preparation with 

 boiling phenolfuchsin and then washing out in 4 per cent, sul- 

 phuric acid. 



The yeasts used for these observations were natural cultivations 

 of ordinary bottom yeasts. The \ east was shaken up with dis- 

 tilled water and then, after settling, the fluid decanted ofl'. The 

 sediment, after having been thus treated several times, was kept 

 for the observations. — Cciitralbl . f. Baktcriol . u. J'arasi'tcnk., 

 xii, J8g2. pp. S37 50. 



Sterilization of Water by Pressure. — MM. Rouart, Gen- 

 este, and Herscher have constructed an apparatus for sterilizing 



