CHAPTER X. ,113 



GUDERNATSCH (Zeit. iviss. Mikr., xxiv, 1908, p. 358) washes the 

 slide well with potash soap, and arranges the sections on it whilst 

 still wet. HELLY (ibid., 1906, p. 330) passes it two or three times 

 over the flame of a Bunsen burner. 



Tap water seems preferable to distilled water ; it seems to spread 

 better and give a stronger adhesion. NUSBAUM adds a trace of gum 

 arabic (1 or 2 drops of mucilage to a glass of water) ; APATHY (Micro- 

 technik, p. 126) adds 1 per cent, of Mayer's albumen ( 187) ; and 

 HENNEGUY (Lecons sur la Cellule, 1896, p. 62) takes a 1 : 5,000 solution 

 of gelatin, with a trace of bichromate of potash, added just before 

 using, and dries the slides exposed to light. Similarly, BURCHARDT 

 (Jena Zeit., xxxiv, 1900, p. 719). 



Some workers have used alcohol (50 or 70 per cent.) instead of water ; 

 but this I believe to be now generally abandoned. 



This is the most elegant method of any, as there is nothing on 

 the slide except the sections that can stain, or appear as dirt in the 

 mount. Tissues do not suffer from the drying, provided the material 

 has been properly imbedded. Sections stick so fast by this method 

 that they will stand watery or other fluids for weeks, so long as they 

 are not alkaline. When successfully performed it is quite safe, 

 provided that the sections are of a suitable nature. They must be 

 such as to afford a sufficient continuous surface, everywhere in con- 

 tact with the slide. Sections of parenchymatous organs stick well ; 

 sections of thin-walled tubular organs stick badly. Sections of 

 chitinous organs 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. Untersuchungsmethoden, 

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



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

 Internal. Monatschr.f. Anat., iv, 1887, p. 42). White of egg, 50 c.c. ; 

 glycerin, 50 c.c. ; salicylate of soda, 1 grm. Shake them well 

 together, and filter into a clean bottle. The filtering 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 



M. 8 



