550 



summary of c('i;i:i:nt researches relating TO 



be stained by anilin dyes, such as sudan iii. sharlach R ; by basic anilin 

 dyes which depend for their action on hydrolysis of the fat, but not by 

 acid dyes. Certain lipoid substances, however, can be stained with acid 

 fuchsin. These substances must possess basic properties, and the stain- 

 ing is a result of the chemical reaction between the base and the acid 

 Nile blue sulphate A was found to stain fat red, the peculiar result 

 being due to an oxazine base in the dye, which in watery solutions 

 slowly changes into an oxazone, red in colour and soluble in liquid fat. 

 Weigert's and Altmann's methods of mordanting with potassium 

 bichromate are discussed, and an investigation of the bichromate hema- 

 toxylin method has yielded an interpretation of Marchi's method. 



Apparatus for Romanowsky Staining.*— C. Schilling describes a 

 simple apparatus (fig. 67) for facilitating staining. It consists of two 



graduated tubes of equal bore, joined by a 

 cross-piece. From the bottom of each tube 

 leads a narrower tube to a stop-cock, by 

 which both can be opened simultaneously. 

 A small funnel receives the drop from each 

 tube and conducts the mixed stain to the 

 preparation. One tube contains methylen- 

 blue (med. Hochst) 2 grm., borax 5 grm., 

 water 1)3 grm., diluted 1 in 50 with water ; 

 the other contains eosin B (A. extra Hochst) 

 0*2 grm. in 1000 grm. of water. The 

 advantage of this method is that the mixing 

 takes place uniformly and the staining is 

 more rapid. 



Methods of Staining Tubercle Bacilli.f 

 S. Rosenblat, after a comparison of the 

 staining methods of Gasis, Ziehl, and Much, 

 has come to the conclusion that the first- 

 named method is of little value. It throws 

 no light upon the minute structure of the 

 tubercle bacillus, nor is it of any practical 

 value in routine diagnostic work. The 

 method is very complicated. Much's modi- 

 fication of Gram's method may elucidate mor- 

 phological points of importance, particularly in the case of young forms. 

 It is of no use as an aid to the search for tubercle bacilli in sputum or 

 in smears from animal tissues. There are also troublesome complica- 

 tions in this method. For the demonstration of the organisms, the best 

 method is that of Ziehl, which gives a clear and distinct picture. The 

 author considers that the granules shown in preparations according to 

 the method of Much are not developmental forms, but degeneration 

 products in bacilli which have lost their acid-fast membrane. A Ziehl- 

 Gram combination throws some light upon the minute structure of the 



Fig. 07. 



organism. 



* Centralbl. Bakt., lte Abt. Orig., lviii. (1911) pp, 264-5. 

 t Centralbl. Bakt., 1« Abt. Orig., lviii. (1911) pp. 173-92. 



