ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 515 



pronounced if the surrounding tissue be quite decolorized with alcohol. 

 If, however, decoloration be not carried so far, it will be found that in 

 addition to the fungus, the nuclei of the surrounding tissue are blue and the 

 protoplasm red. As glycerin extracts the blue colour, preparations must 

 be mounted in balsam. 



As dehydration conducted in the ordinary manner would deprive the 

 sections of colour, it is necessary, after having washed in distilled water, to 

 pass rapidly through absolute alcohol to the slide, where the excess of spirit 

 is to be quickly blotted up. A drop of thick cedar-oil is then added, and 

 as this soon hardens, balsam need not be applied. Thus prepared, specimens 

 have kept well for five years. 



Double Staining with Echein-green and Carmine.* — Mr. J. D. Beck 

 states that he has met with splendid results by a combination of echein- 

 green (an acid dye) and carmine. He first stains the sections with the 

 echein-green for five seconds to ten minutes. They are then washed in 

 distilled water from 150° to 212*^ Fahr. for two to twenty minutes. If time 

 allows, cold water acting for a longer time acts as well. Alcohol first of 

 60 and then of 95 per cent, hastens the process. The object of the fore- 

 going is to remove all acidity before staining with carmine. The sections 

 are tested for acidity by allowing some water from the slide on which a 

 section is placed to drop on the tongue, or to add some carmine to the slide 

 water and examine under the Microscope to see if any precipitate occurs 

 when ammonia carmine is added. If all traces of acidity be removed, the 

 carmine staining may be proceeded with. 



When sections have a feeble afi&nity for green, the author mounts in the 

 following medium : — White sugar syrup 1 oz., pure glycerin 10 to 30 

 drops ; mix thoroughly. When stained the section is first cleared in pure 

 glycerin, the surplus of which is washed off with water; the latter is 

 evaporated and then the syrup added. 



Stained Permanent Preparations of Cover-glass Cultivations.f — Dr. 

 F. Lipez's method for preparing and staining cover-glass preparations suit- 

 able for observing under high powers the developmental changes in micro- 

 organisms, consists in first obtaining a thin layer of the nutritive medium 

 previously inoculated to any desired degree with the micro-organism to be 

 examined. The medium is kept in a water-bath at a temperature of 25° or 

 40° C, according as gelatin or agar is used. With this the surface of the 

 cover-glass is moistened and the superfluous matter drained off with blotting- 

 paper. A film about 0*08 mm. thick is thus obtained. The covers are 

 then placed in a moist chamber or in an incubator, and are then withdrawn 

 at definite intervals. They are dried (best over strong sulphuric acid), 

 stained, decolorized, and mounted in balsam. 



The most difficult part of the operation is to decolorize the gelatin or 

 agar without removing the stain from the organisms. The behaviour of the 

 various dyes and of the nutrient layers is very different, but the author 

 mentions, provisionally, that methyl-green is easily removed, and that 

 alcohol and carbonate of potash may in a measure be relied on for de- 

 colorizing. Again, some care is necessary to prevent the "fluidifying" 

 bacteria from being washed away, while of other varieties many stick firmly 

 to the cover even after the medium has been removed. 



New Methods of using Anilin Dyes for staining Bacteria.t — Mr. 

 E. H. Hankin premises that in the methods he describes care must be given 



* The Microscope, vii. (1887) pp. 69-71. 



t Centralbl. f. Bacteriol. u. Parasitenk., i. (1887) pp. 402-3. 



X Quart. Journ. Micr. Sci., xxvii. (1887) pp. 401-11. 



