ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 235 



Toleration of Bacteria for Alcohol and for Acetic Acid.* — C. S. 

 Stokvis has observed the toleration of BacilMs typhosus, B. coli, B. 

 paratyphosus (B), B. prodigiosus, and Vibrio cholerse for alcohol and for 

 acetic acid. Emulsions of estimated numbers of bacteria were prepared 

 from agar cultures of the organisms and treated with varying per- 

 centages of alcohol, and incubated at 37° C. for 24 honrs ; a loopful 

 holding 1-8 mg. of the emulsions was then transferred to a second 

 series of tubes containing 9 c.cm. of water or broth and again incu- 

 bated for 24 hours, and the organisms in the resulting growth were 

 enumerated. 



The author found that marked diminution in the number of B. coli 

 first occurred when the percentage of alcohol had reached 6 p.c. ; that 

 with B. typhosus this occurred first with 8 p.c. of alcohol, this organism 

 being more resistant than B. coli ; with Vibrio cholerse marked inhibition 

 of growth occurred with 3 p.c. of alcohol ; in the case of B. prodigiosus 

 and B. paratyphosus B with between 4 and 6 p.c. of alcohol. 



In similar manner bacterial emulsions are diluted with various per- 

 centages of acetic acid. The author found that in every tube the 

 bacteria were collected in clumps at the bottom, and to obviate this 

 effect the dilutions in broth were at once poured into tubes of gelatiu 

 and plated. Plates of agar were also prepared. Examination of plates 

 after 24 hours showed a complete inhibition of growth with even 

 J-J p.c. of acetic acid. Employing the Bacterium aceti cultivated from 

 beer, and grown on tubes of sloped agar, the author found that even 

 after the addition of 7 p.c. of acetic acid there was still slight growth of 

 this organism. 



Bacterium polychromicum.f — H. Zickes finds that this organism 

 grows well on various media ; it exhibits great polymorphism, appearing 

 as cocci on some media, on others as rods ; it possesses no flagella, and 

 does not form spores. It produces several chemically distinct colouring 

 matters. The yellow substance (Lipoxanthin) occurs on dextrose-agar 

 cultures at 20° C. The blue substance appears on potato ; it dissolves 

 when treated with an alcoholic solution of soda ; an aqueous solution is 

 decolorised by aluminium amalgam, but regains its colour if treated 

 with a small quantity of peroxide of hydrogen ; a watery extract of 

 the potato culture mixed with a little glucose and peptone and inoculated 

 with Bacillus coli, gradually loses its blue and assumes a yellow colour ; 

 the narrow layer under the surface, owing to the acid formation by the 

 B. coli, takes a red-violet tint, which disappears on shaking, but returns 

 after a short while. 



Bacillus coli communis.:}:— Agueda Terreira, A. Bettencourt, and 

 others in four communications report that their researches confirm in 

 great measure the results of the English bacteriologist as regards the 

 general characters of Bacillus coli isolated from the human intestine. 

 They add two points, viz., the power of fermenting lactose and the 

 production of indol at the expense of peptone. With regard to 



* Centralbl. Bakt., lte Abt. Orig., xlviii.(1908) p. 436. 



t Op. cit., 2te Abt., xxi. (1908) pp. 522. 



% Arch. K. Instit. Bacteriol. Carnara, Pestana, ii. (1908) pp. 155-270. 



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