ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
657 
feeblest bacilli, so that when a cultivation bas been left to itself, the 
number of virulent and fertile organisms decreases. 
At a given period a weak inoculation may not reveal any trace of 
virulence. Nevertheless, from the cultivation, quite a generation of 
virulent bacteria may be reared. But in order to bring this evidence to 
light, cultivation methods or strong inoculations must be employed. 
Negative Indol-reaction as a test for the Typhoid Bacillus.* — The 
resemblance, from their morphological and cultivation aspects, of numerous 
bacilli to the bacillus of typhoid, suggests the importance of having 
some specific test which may be easily applied in making a differential 
diagnosis between the bacillus of typhoid and other bacteria. 
Recent observations have shown that potato cultivations do not 
afford a certain criterion ; but after experimenting with sixteen kinds of 
bacteria, Dr. S. Kitasato found that these, when cultivated in bouillon, 
produced indol, while the typhoid bacillus did not. 
The indol was tested for by Salkowski’s method, that is, by treating 
the cultivations with a solution of nitrite of potash, and then adding a 
few drops of strong sulphuric acid. With this test the typhoid bacillus 
remained colourless, while the other sixteen bacilli assumed the cha- 
racteristic red hue. 
Careful chemical analysis also constantly showed the absence of 
indol from the typhoid cultivations. 
As all these pseudo-typhoid bacilli developed on potato quite dif- 
ferently from the real typhoid bacillus, the author concludes that the 
negative indol reaction is in itself no better test that the growth on 
potato is. 
Canestrinis’ Bacteriology.-f — The ‘ Bacteriology ’ of Gr. and R. 
Canestrini is quite up to date on all branches of the subject. The 
general part of the work deals with the morphology and biology of 
micro-organisms, and also their mode of infection, while at the same 
time prophylaxis and hygienic precautions are not neglected. The various 
apparatus, cultivation, and staining methods as applied to the examina- 
tion of water, air, and earth are clearly and precisely described. The 
special part deals with a number of micro-organisms pathogenic to man 
or the lower animals, and is very thorough. 
Arloing, S. — Un mot sur l’immunite naturelle. (A word on natural immunity.) 
Arch, de Med. Exper. et d'Anat. Pathol., January 1890. 
Beyer inck, M. W. — Le Photobacterium-luminosum : Bacterie lumineuse de la 
mer du Nord. ( Photobacterium luminosum: Luminous Bacterioid of the North 
Sea.) Archives Neerlandaises, XXIII. p. 401. 
Boll, F. — Zur Desinfektion der Hande. (On disinfection of the hands.) 
Deutsche Medic. Wochenschr ., 1890, No. 17, pp. 354-7. 
Charrin et Roger. — Nouvelles recherches sur les proprietes microbicides du 
serum. (New researches on the microbicidal properties of serum.) 
Compt. Pend, de la Soc. de Biol., 1890, No. 14, pp. 195-8. 
Giard, A. — Nouvelles recherches sur les bacteries lumineuses pathogenes. (New 
researches on pathogenic luminous Bacteria.) 
Compt. Pend, de la Soc. de Biol., 1890, No. 14, pp. 188-91. 
* Zeitschr. f. Hygiene, vii , No. 3. See Bot. Centralbl., xli. (1890) pp. 364-5. 
t ‘ Batteriologia,’ R. e G. Canestrini, 8vo, Milano (Hoepli), 1890, 29 pis. Cf. 
Centralbl. f. Bakteriol. u. Parasitenk., vii. (1890) pp. 131-2. 
