ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
405 
The unfavourable action of electric and sunlight on the growth of 
the typhoid bacillus on gelatin is not to be ascribed to the direct action 
of the light upon the bacilli themselves, but upon the changes set up in 
the media, and it is suggested that these changes may be due to the air 
becoming ozonized under the influence of the light-rays. 
Mixed Cultivations.* — To verify the constant occurrence of a certain 
microbe, to be intimately acquainted with its morphology and biology, 
are, says M. Nencki, insufficient data for asserting that this particular 
microbe is the sole cause of the disease ; indeed, if this were so, dealing 
with pure cultivations, say of cholera, diphtheria, &c., would be 
extremely dangerous for the bacteriologist. The author then states 
that in connection with the bacillus of symptomatic anthrax there is 
found a facultative anaerobe, M. acidi paralactici, and examination of the 
action of these microbes towards sugar showed that the bacillus acting 
alone formed from grape-sugar butyric acid, then acetic acid, and the 
optically inactive lactic acid, while the micrococcus when alone decom- 
posed the sugar into paralactic acid. If, however, the sterile sugar 
solution were inoculated with both microbes at once, the ferment action 
was much more rapid, and the fermented fluid contained, besides the meta- 
bolic products peculiar to both microbes, a considerable quantity of 
butyl alcohol. Hence the simultaneous action of two microbes is capable 
of producing a compound which neither alone is able to develope. 
From this point of view the author explains disease ; it is, in fact, 
duo to a mixed infection, a symbiosis of micro-organisms, none of which 
alone would be able to produce that succession of morbid phenomena, 
but which, when acting in concert, bring about a condition recognizable 
as a specific disease, and he supports his argument by pointing out that 
the cholera bacillus alone is unable to call forth the typical cholera 
asiatica. 
The author is of opinion that the present tendency of inducing 
alcoholic fermentation by means of pure cultivations of yeasts will in 
time be supplanted, since he has noted that when two different kinds of 
Schizomycetes act on sterile grape-sugar solution, they do so more 
energetically when in co-operation than when alone. 
In contrast to this symbiosis and the results of mixed cultivations 
may be set those of enantiobiosis ; this is indeed nothing but a symbi- 
osis, but the action of the microbes, instead of being an intensifying one, 
is neutralizing ; for example, pure cultivations of two different microbes 
acting alone on albumen will decompose it most energetically, but when 
acting in combination the fermentation is not only less active, but in a 
few days ceases altogether. 
Bacteriological Examination of Drinking-water. j — Dr. A. Eeinsch 
records the results of a series of experiments made with Elbe water. 
The cultivation medium used was Koch’s 10 per cent, meat-pepton- 
gelatin, and the object of the experiments was to determine, if possible, 
the proper alkalinity for this medium, the text-books merely stating that 
the reaction should be slightly alkaline. The author gives two tables 
in which are drawn up the results from adding definite quantities of 
* Centralbl. f. Bakteriol. u. Parasitenk., xi. (1802) pp. 225-8. 
t Op. cit., x. (1891) pp. 415-8. 
