ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 623 



Influence of Human Tubercle Bacilli on Frogs.* — Herr V. Sion 

 contests the views of Bataillon, Terre, and others as to the influence of 

 human tubercle bacilli on frogs. The author finds that it does not 

 excite any characteristic lesions, nor does it become generalised in the 

 body of this animal. It does not undergo any fundamental changes of 

 shape, staining reaction, &c. ; its virulence remains unaltered ; and it 

 does not endow the frog with any soluble substance which can impart 

 immunity to guinea-pigs or increase their resistance. 



Growth of Tubercle Bacilli on Mucus. f — Dr. P. Komer finds that 

 tubercle bacilli grow with extreme facility in mucus obtained from 

 healthy persons. As a medium mucus suffers from contamination with 

 numerous microbes which may obscure the growth of the tubercle bacilli, 

 and all attempts to sterilise it failed. The favourable growth of the 

 tubercle bacilli in mucus is presumed to be due partly to its physical 

 characters and partly to nutrient substances dissolved in it. 



Bacillus pyocyaneus. £ — Dr. P. Krause found that currents of high 

 tension (Tesla) have no direct action on cultures of Bacillus pyocyaneus 

 and other bacteria, but that, owing to the heat developed, the cultures 

 are killed or much damaged. When placed within a solenoid no diminu- 

 tion of growth was observed, but the green pigment of B. pyocyaneus 

 was altered to yellow, and the red of B.prodigiosum became pale rose. 



When existing in symbiosis with Streptococcus pyogenes, it was noticed 

 that the pigment formation of B. pyocyaneus might be greatly diminished 

 or even suppressed, so that colourless pus might contain B. pyocyaneus 

 without its presence being recognised by the naked eye. 



Under anaerobic conditions the vitality and chromogenic function 

 were impaired or lost. 



B. pyocyaneus produces two pigments : the blue, pyocyanin, is specific, 

 and when dissolved by chloroform can be used to distinguish it from 

 other fluorescing bacteria ; while the green fluorescing pigment is soluble 

 in water, and is formed by numerous other bacteria. 



Effect of Pyocyanase on Anthrax.§ — Prof. K. Emmerich and Dr. 

 Saida describe the morphological changes in anthrax bacilli under the 

 influence of pyocyanase. The bacterium swells up, becomes granular 

 and finally almost transparent. The dissolution takes place even more 

 quickly in vivo than in vitro, if directly after artificial infection pyo- 

 cyanase solution be injected intravenously or subcutaneously. The 

 changes observed are ascribed to the action of a proteolytic enzyme, 

 pyocyanase, which was obtained by filtering a fluid culture, then dia- 

 lysing, and precipitating with absolute alcohol. The pyocyanase thus 

 obtained was dried in vacuo over sulphuric acid. When used it was 

 dissolved in distilled water. Its reaction should be alkaline, as acid 

 solutions have no effect. The preparations were stained by Nakanishi's 

 method. The authors claim that their observations have a direct bearing 

 on the cure of infectious disease and artificial immunity. 



Bacteria in the Stomach of the Cat.|| — Dr. J.Weiss made an in- 

 vestigation of the bacteria in the stomach of the cat ; among the more 



* Centralbl. Bakt. u. Par., l u Abt., xxvii. (1900) pp. 710-20. 



t Tom. cit., pp. 705-9. J Tom. cit., pp. 769-75. § Tom. cit., pp. 776-87 (1 pl.> 



|| Journ. Applied Microscopy, iii. (19u0) pp. 827-35. 



