FIXING AND STAINING BLOOD-FILMS. 221 



and another cover. The utmost care must be taken to avoid all 

 pressure, as the after-appearance of the red corpuscles depends 

 almost entirely upon the way in which the manoeuvre is carried 

 out. The covers are then gently and rapidly slid off one another, 

 and dropped with the wet side downwards into the fixing solution. 

 This is made up of: — 



Absolute alcohol saturated with eosin ... •••25 c.cm. 



Pure ether ... ... ... ... 25 c.cm. 



Sublimate in absolute alcohol (2 grm. to 10 c.cm.)... 5 drops 



(more or less). 



The quantity required for use at one time, which may be 5 to 

 10 c.cm. for four cover-glasses, should be poured into a wide- 

 mouthed bottle or flat dish, and may be used several times over if 

 it be ])reserved from evaporation. (I generally keep the thin 

 liquids in different bottles, and make up the required amount in 

 the above proportion before using it.) The fixation of the ele- 

 ments is practically instantaneous, but the cover-glasses should be 

 allowed to remain in the solution for at least three or four minutes 

 to fix the film to the cover. They are then taken from the solu- 

 tion by forceps (steel forceps will do), and wash rapidly but 

 thoroughly by waving them to and fro in a small basin of water. 

 They are then stained for one minute (not longer) in a saturated 

 watery solution of methylene blue, and again rapidly washed in 

 water. Next, they are quickly dehydrated in absolute alcohol, 

 which at the same time removes the excess of methylene blue, 

 cleared in xylol, and mounted in xylol balsam on a slide. 



The whole process need not occupy more than six or seven 

 minutes ; but, on the other hand, any portion of it may be pro- 

 longed without injury to the specimen. The fixation may be con- 

 tinued for twenty-four hours and the washing for the same time ; 

 but if the staining with methylene blue be prolonged for a minute 

 or two, it becomes necessary to use an inconveniently large amount 

 of absolute alcohol to remove the excess of the stain, and the 

 eosin is apt to be washed out at the same time. The red corpus- 

 cles are stained pink, the nuclei a deep blue, the bodies of the 

 leucocytes in varying shades of pink ; the eosinphile and baso- 

 phil granules in the leucocytes are well brought out ; the blood- 

 plates are stained a fainter blue than the nuclei, and organisms are 

 also well stained. 



IXTERNATIONAL JOURNAL OF MICROSCOPY AND NATURAL SCIENCE. 



Third Series. Vol. VII. Q 



