2176 Journal of Applied Microscopy 



Place some bacteria on a slide under a cover-glass ; notice how they swarm 

 around air-bubbles and finally collect at the margin of the cover-glass, where 

 oxygen is most available. Make another preparation and seal the edge of the 

 cover-glass with olive oil or vaseline in such a way as to prevent the access of 

 oxygen, notice that the bacteria ultimately become sluggish and come to rest. 

 If a filament of Spirogyra, or a bit of a leaf of some water plant be included 

 with the sealed bacteria, oxygen may be produced by exposing the preparation 

 to light. Cover the microscope, upon which the slide rests, with a tight box 

 which will exclude all light. When it is found that the bacteria have come to 

 rest, remove the box and examine immediately to note the return of motility. 

 University of Michigan. HOWARD S. Reed. 



A Review of the Methods of Staining Blood. 

 . V. 



D. Neutral Stains. 



1. Acid Fuchsln=Methylen YAwt.—EhrlkJis neutral compound of acid fuch- 

 sin and methylen blue is made as follows : To 5 volumes of a saturated watery 

 solution of acid fuchsin is added gradually with shaking 1 volume of a strong 

 watery solution of methylen blue, then 5 volumes of distilled water. After some 

 days the fluid is filtered. Methyl green may be substituted for methylen blue in 

 this solution. 



Preparations should be stained from 2 to 5 minutes, washed in water very 

 superficially, dried with filter paper, and after air-dry mounted in balsam. Ery- 

 thocytes stain red, acidophile granules bright puple, neutrophile granules violet. 



Tamassia (1894) claims, that by the use of the following compound of acid 

 fuchsin and methylen blue, he has demonstrated the presence of neutrophile 

 leucocytes in the blood of various mammals : 



Saturated watery solution of acid fuchsin 5 c. c. 



" " " " methylen blue 1 c. c. 



Distilled water - - - - - 5 c. c. 



2. PhIoxin=Methylen Blue. 7^^;i-^«^<?r^^r (1901) gives this formula for a neu- 

 tral stain : 



Saturated watery solution of methylen blue - 50 c. c. 



" " " " phloxin - - 20 c. c. 



Alcohol, 95 per cent. - - - - 30 c. c. 



Distilled water - - - - - 60 c. c. 



These are all mixed indiscriminately together and a bluish solution results. A 

 precipitate generally falls and the stain should be shaken before using. 



Blood films fixed by dry heat at 115° to 120°C. for 20 minutes or in equal 

 volumes of alcohol and ether are stained 1 to o or 4 minutes, washed, dried and 

 mounted in balsam. Nuclei stain various shades of blue, the nuclei of the lym- 

 phocytes stain deeply and around their periphery numerous basic granules are 

 often seen. Acidophiles, nuclei light blue, granules bright red, almost brilliant. 



