ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 215 



the two solutions are mixed together. The blood is sucked into a 



Thoma-Zeiss pipette up to the - 5 mark, and then diluted with the 



staining solution up to 1-20. Five minutes are allowed for the mixing 



of the blood and stain in the pipette, after which the contents are blown 



into an Elzholz counting chamber, the capacity of which is - 9 of a 



cubic millimetre. The total number, when the blood has been diluted 



200 

 twenty times, is multiplied by or 22 ■ 2, the product being the number 



per cubic millimetre. The solution may be used for film preparations, 

 and is specially adapted for differentiating the varieties of leucocytes. 



New Staining Method for Red Corpuscles in Sections. * — The 

 method adopted by N. Petroff for staining red corpuscles depends on 

 the fact that they pick up pigment from the malachite-green group 

 when they are also treated with picric acid and alcohol. The prepara- 

 tions are fixed in Miiller's fluid or in formalin, and imbedded in paraffin. 

 The sections are stuck on the slide with water. The paraffin is removed 

 with xylol, and they are then washed with alcohol and xylol. Thereafter 

 follow: — (1) Staining with Bismarck-brown (saturated solution in 1 p.c. 

 acetic acid) 10-15 minutes, or with lithium or borax-carmine for 20-30 

 minutes. (2) Washing in water and then staining for 10-15 minutes 

 with 20 p.c. aqueous (i.e. five times diluted alcoholic) solution of mala- 

 chite-green, brilliant green, or Victoria-green. (3) Washing with water, 

 followed by staining for 1-11 minutes by Van Gieson's method, or with 

 aqueous solution of picric acid five times diluted. (4) Washing with 

 water, followed by rapid dehydration in absolute alcohol ; lastly xylol and 

 balsam. By this method, which is really quite simple and easy of exe- 

 cution, the red corpuscles are stained emerald-green, the rest of the 

 tissues being yellowish-brown or yellowish-red. 



Fat-Staining.! — Dr. «J- Lewinson stains fat by a modification of 

 Wolters' method. The material is fixed in Miiller's fluid for 2-6 

 weeks, and, after dehydration in 70 p.c. and 85 p.c. alcohol, is imbedded 

 in celloidin. The sections are stained in hematoxylin solution 

 (2 grm. hematoxylin dissolved in a little absolute alcohol and added 

 to 100 ccm. of 2 p.c. acetic acid) for 12 hours at a temperature of 40° C. 

 Alter washing in water, they are treated with a 1 p.c. aqueous solution 

 of permanganate of potash for 10-15 minutes. The sections are again 

 washed in water, and then immersed in 2 p.c. oxalic acid or a mixture 

 of 2 parts 2 p.c. oxalic acid and 1 part 2 p.c. sulphite of potash for 

 5 minutes. They are next washed in water, and mounted in the usual 

 way, or may be contrast-stained with borax-carmine and picric acid to 

 show the nuclei and protoplasm of the cells. 



By the foregoing procedure even the smallest particles of fat are 

 distinctly stained. 



Modification of Pitfield's Method for Staining Flagella. % — Dr. 

 J. B. Smith has found the following modification of Pitfield's method 

 for staining flagella very reliable and easily carried out. The mordant 

 is made as follows : — A saturated solution of perchloride of mercury, made 



* Bolnicznaja G'azeta Botkina, 1899. See Zeitschr. wiss. Mikr., xvii. (1900) p. 359. 

 t Zeitschr. wiss. Mikr., xvii. (1900) pp. 321-7. Cf. this Journal, 1891, p. 425. 

 % Brit. Med. Journ., 1901, i. pp. 205-G. 



