656 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Analysis of its composition showed that its formula is c 10 H n N. 
With regard to the origin of this alkaloid it cannot he doubted that 
it is a product of the chemical decomposition of the albuminoid mole- 
cules of the peptonized agar, produced daring the life of Bacterium Allii. 
Chromogenic Function of Bacillus pyocyaneus.* — Although, says 
M. C. Gessard, the earlier bacteriologists assumed that the hues pro- 
duced by chromogenic bacteria were invariably and constantly associated 
with their vital activity, it now seems more probable that the presence of 
pigment represents a symptomatic reaction of the microbe which pro- 
duced it, since the colouring matters obviously vary with the slightest 
differences in the cultivation medium and its environment. Hence it 
would be more in accord with our present knowledge to state the law 
thus : — The same microbe may present different biological and morpho- 
logical characteristics, and identical morphological and biological 
characters may be found in different microbes. 
This law is derivable from the colour appearances of the bacillus of 
blue pus, which is distinguished by producing a blue crystallizable pig- 
ment, pyocyanine. This blue pigment is easily recognizable on and isolable 
from dressings of wounds, but when B. pyocyaneus is cultivated in beef 
or veal broth, the pigment produced is not a pure blue, but a greenish 
blue, and is further marked by a certain degree of fluorescence. Both 
of these characteristics can be separately cultivated, the pigment in 
commercial peptone dissolved in 50 parts of water and the fluorescence 
in egg-albumen. A further characteristic of this fluorescence is that it 
is destroyed by addition of acid and increased by alkalies. 
Hence the chromogenic function of B. pyocyaneus varies with the 
medium, and from these varieties the author deduces the law above 
stated. 
Pathogenic Microbes in filtered water of the Rhone-t — MM. Lortet 
and Despeignes have found that, although the Rhone water when 
filtered contains only 7000 germs per litre, yet there passed through a 
Chamberland filter a considerable deposit consisting of organic and 
inorganic material remains. 
In order to ascertain if this deposit from potable water reported to 
be of excellent quality, and in appearance perfectly filtered, contained 
pathogenic microbes in any considerable quantity, the authors inoculated 
guinea-pigs. Most of the animals died with suppurative visceral lesions, 
the organs most severely and most often affected being the liver and 
lungs. 
These results indicate that this apparently good water is fraught 
with danger to the public health, and when the pressure on the filterin g 
beds rises, as it must do whenever the river swells, this danger increases, 
since the deposit on the gravel is then detached, and thus becomes mixed 
up wdth the water distributed throughout a town. 
Loss of virulence in cultivations of Bacillus anthracis.J — From obser- 
vations made on cultivations of Bacillus anthracis, M. S. Arloing concludes 
that in one cultivation the bacilli do not possess the same virulence nor 
the same vegetative potentiality. Senescence first shows itself in the 
* Comptcs Rend us, cx. (1890) pp. 418-20. f T. c., pp. 353-5. 
+ T. c., pp. 939-41. 
