ZOOLOGY AND BOTANY, MICROSGOPY, KTC. 403 



B. Technique.* 

 (4) Staining' and Injecting. 



Staining Spirilla with Formol-violet. — P. Spehl {G.R. Soc. Biol., 

 1918, 81, 305-6). 1. Spread a thin film on cover-slip and dry. 



2. Mordant with acetic formol (Rnge) for five minntes. Repeat this 

 process twice. (Formol •!, acetic acid 1, distilled water up to 100.) 



3. Replace the acetic formol by 10 p.c. aqueous solution of chromic 

 acid. Allow to act for ten minutes. 4. Wash in absolute alcohol for 

 two minutes ; then flame. 5. Stain with warm formol gentian- violet 

 for two minutes. 6. Wash rapidly in water. 7. Treat with Lugol's 

 iodine solution for five minutes. <s. Wash, dry and mount. 



By this process cell protoplasm is stained violet, the nuclei black. 

 Bacteria are black, Spirilla violet, or more often black. J. E. 



Double Staining of the Tubercle Bacillus : a Modification of 

 Spengier's Method.— P. Spehl (6'. R. Soc. Biol., 1918, 81, 248-9). In 

 the method the bodies of the bacilli are stained red, Much's granules black, 

 and the remainder of the preparation pale yellow, and is carried out as 

 follows : — Smear a thin film of the sputum on a cover-glass, dry, fix with 

 absolute alcohol one minute, and flame. Stain with a freshly-prepared mix- 

 ture of Ziehl's fuchsin 3 parts and carbolic gentian-violet 2 parts, for 2-3 

 minutes warm, or if preferred for 15-30 minutes cold. Replace the stain 

 by Spengier's picric alcohol cold (sat. aq. sol. picric acid 60, alcohol 40), 

 and allow to act for one minute. Replace the picric alcohol by 60 p.c. 

 alcohol, and wash the film three times in this solution. Decolorize for 

 20 seconds in nitric acid, 15 p.c. solution. Complete decolorizing with 

 60 p.c. alcohol. Counterstain for one minute with picric alcohol. Wash 

 in water, dry and mount. J. E. 



Metallography, etc. 



Testing Hardness of Metals by the Boyelle-Morin Apparatus. — 

 •C. J. BowEN Cooke (Jourii. of Inst, of Mechanical Engineers, 1918, 

 5, 331-4, 4 figs.). The essential part of tliis apparatus consists of 

 a tube a carrying a hardened steel ball c, and a rod h enlarged at the 

 lower end to slide freely in a. Interposed between the lower end of b 

 tnd the ball c is a cylinder or cube d cut from a bar whose hardness has 

 been determined in a 3000-kilogram Brinell machine. The apparatus 

 must be held vertically, with the ball c resting on the surface e to be 

 tested, and the top of the rod h struck sharply with a hammer causing 

 the ball to indent d and e. The diameters d and e of the indentations 

 are measured by the scale and a magnifying glass, and the correspond- 

 ing hardness numbers are read oft" on a specially graduated slide-rule. 



* This subdivision contains (1) Collecting Objects, including Culture T'ro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Embedding and Microtomes ; 

 (4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, etc.; 

 ^6) Miscellaneous. 



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