252 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Staining Living* and Dead Bacteria.* — H. Kayser gives a brief 

 account of his application of the method first described by Proca by 

 which living and dead organisms may be distinguished. His procedure 

 is as follows : — Thin coverglass film? are prepared and gently warmed. 

 When these are dry, methylen-blue is applied for two or three minutes 

 and then carefully washed. The preparation is put into dilute carbol-. 

 fuchsin (1 in 10) for five or ten seconds, dried, and mounted. Living 

 organisms take the blue stain, while those that have lost their vitality 

 appear red. By this method variations in the power of resistance of 

 dilTerent organisms to various poisons may readily be demonstrated. In 

 old cultures of organisms, such &s BaciUus coli, it may similarly be show u 

 that a large number of devitalized forms are present. The process 

 may be simplified by usins" a solution containing 8 c.cm. of carbol-fuchsin 

 solution in 100 c.cm. of distilled water and 100 c.cm. of Loeffler's 

 methylen-blue. 



Bleaching of Hsematoxylin Preparations.f — D. Carazzi discusses 

 the phenomenon, frequently observed, that microscopical specimens 

 stained with haematoxylin are liable to become bleached in the course 

 of some mouths. He mentions the work of Metcalf, who attributed this 

 to slight acidity of the Canada balsam, and recommended therefore that 

 preparations should be exposed to ammonia turner for a second or so 

 before mounting. The present writer considers that the deterioration is 

 due neither to the acidity of the balsam nor of the air, but to changes 

 in hematoxylin preparations during dehydrating, clearing and embed- 

 ding. The change occurs principally in sections of material stained in 

 toto before embedding and cutting. No bleaching occurs in specimens 

 stained with a hematoxylin solution described by the author. This 

 contains hematoxylin ■ 5 gm., potassium iodate '01 gm., alum 25 gm., 

 glycerin 100 c.cm., distilled water 400 c.cm. 



Staining Failures. f — B. Rawitz gives an account of unsuccessful 

 attempts to make use of sodium tungstate with cochineal, carmin or 

 haematin, and of aluminium acetate with hematoxylin, hematin, or 

 cochineal, as staining re-agents. Clear solutions of rich colours were 

 obtained, but the staining power was absent. In the view that in the 

 first case excessive alkalinity, in the second excessive acidity, might be re- 

 sponsible for these disappointing results, he corrected these conditions, 

 but with no greater success than before. 



Action of Ultra-violet Rays on the Staining of Acid-fast Bacteria.§ 

 A. Rochaix and (1. Colin exposed to the light of a mercury vapour quartz 

 lamp the following bacilli : Bovine tubercle, Grass bacillus ii, Smegma, 

 Milk bacillus. Bacillus ii Tobler, and the Butter bacillus. The bacilli 

 were irradiated in the dry and wet state for times varying from 10 

 minutes to 4 hours, and their stain ability was afterwards tested by the 

 Ziehl, Much, and Gram methods. When irradiated in the dry state the 

 microbes did not stain by any of the methods, though the resistance 

 varied according to the species. There was no parallelism between the 



* Centralbl. Bakt., Ite Abt. Orig., Ixii. (1912) pp. 174-6. 

 t Zeitschr. wiss. Mikrosk., xxviii. (1911) pp. 271-4. 

 X Zeitschr. wiss. Mikrosk , xxviii. (1911) pp. 261-7. 

 § Gomptes Rendus, clii. (1911) pp. 1253-6. 



