122 CHAPTEIi X. 



are very unsafe. The larger and thinner sections are, the 

 better do they stick, and vice versa. Sections from chromic 

 or osmic material adhere less well than sections from alcohol 

 or sublimate material. 



By taking a staining solution instead of pure water for expanding, 

 the sections can be got to stain at the same time, and so be brought into 

 balsam without passing through alcohol ; see MAYER, Mitth. Zool. Stat. 

 Neapel, xii, 1896, p. 320 ; SCHMORL, Path.-hist. Untersuchungsmethodtn, 

 1897, p. 38; SMITH, Journ. Anat. Phys., xxxiv, 1899, p. 151. 



187. MAYER'S Albumen (Mitth. Zool. Stat. Neapel, iv, 1883; 

 Interned. Monatschr.f. Anaf. } iv, 1887, p. 42). White of egg, 

 50 c.c. ; glycerin, 50 c.c. ; salicylate of soda, 1 grin. Shake 

 them well together, and filter into a clean bottle. The filter- 

 ing may take days or a week, but the preparation does not 

 spoil meanwhile. 



FRANCOTTE shakes up the albumen with a few drops of 

 acetic acid before adding the other ingredients, and finds 

 the filtering greatly quickened. So do I. Be careful with 

 the acid. 



A very thin layer of the mixture is spread on a slide with 

 a fine brush and well rubbed in with the finger (I prefer a 

 small rubber " squeegee "). The sections are laid on it and 

 pressed down lightly with a brush (if they will bear it). 

 The slide may then be warmed for some minutes on a water- 

 bath, and the paraffin removed with a solvent. 



It is not necessary to warm the slide at all; the paraffin 

 can he removed in the cold if desired by putting the slide into 

 toluol, xylol, or the like. But the slide must, in any ease, 

 be treated icith alcohol after removal of the paraffin, in order 

 to get rid of the glycerin, which will cause cloudiness if not 

 perfectly removed. 



This method allows of the staining of sections on the slide 

 with perfect safety, both with alcoholic and aqueous stains, 

 provided they be not alkaline. 



According to my experience, the albumen method is abso- 

 lutely safe, provided that alkaline fluids le avoided in the 

 after-treatment. It has the defect that certain plasma 

 stains (not chromatin stains) colour the albumen very 

 strongly, and cannot be removed from it, and that sections 

 are not expanded by it. 



