ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
565 
Conditions affecting Bacterial Life in Thames Water.* — Dr. E. 
Frankland, who has for many years busied himself with the investigation 
of the waters supplied to Londoners, has, since May 1892, been making 
monthly determinations of the number of bacteria capable of develop- 
ment on a peptone-gelatin plate in a given volume of Thames water, 
collected at the intakes of the metropolitan water companies at Hampton. 
The number of microbes per ccm. of water varied during this time 
between 631 and 56,630. As a rule, the highest numbers were found in 
winter, or when the temperature of the water was low, and the lowest in 
summer, or when the temperature was high. The author comes to the 
conclusion that his comparisons demonstrate that the number of microbes 
in Thames water depends upon the rate of flow of the river, or, in other 
words, upon the rainfall, and but slightly, if at all, upon either the 
presence or absence of sunshine or high or low temperature. Without 
denying that the researches of Marshall Ward prove that sunlight is a 
powerful germicide, Dr. Frankland thinks that it is probable that its 
potency in this respect is greatly diminished, if not entirely annulled, 
when the solar rays have to pass through a stratum of water, even of 
comparatively small thickness, before they reach the living organisms. 
Extracellular Destruction of Bacteria. | — In his sixth memoir on 
Immunity, M. E. Metschnikoff deals with the extracellular destruction of 
bacteria in the organism, a doctrine put forward by R. Pfeiffer, who 
found that cholera vibrios disappear when injected into the peritoneal 
sac. The inference from this observation is that now there was no 
need to ascribe to phagocytes a microbicidal power ; for the vibrios dis- 
appear through the direct influence of the exudation, the destruction 
being proportional to the immunity of the animal. The author defends 
his position with numerous experiments and verbal arguments, his main 
conclusions being that the extracellular destruction of vibrios in the 
peritoneal sac is not to be ascribed to an endothelial or other secretion, 
but to a bactericidal manifestation of the liquid discharged by leucocytes 
attacked or broken up during the phase of phagolysis. The Pfeiffer 
phenomenon and also phagolysis disappear if the leucocytes be reinforced 
by a previous injection of bouillon ; the animal is then able to free itself 
of the vibrios by an intense phagocytic action ; and, taken altogether, the 
cholera peritonitis of guinea-pigs is a well-marked example of phago- 
cytosis. 
The animal organism, under the influence of preventive serum, gets 
rid of the cholera vibrios more often by the aid of a typical phagocytosis 
than by means of an extracellular destruction. The Pfeiffer phenomenon 
occurs only in those cases where the vibrios penetrate into & medium 
which already contains a sufficient number of leucocytes, and only in 
those animals the leucocytic products of which possess a considerable 
bactericidal force. The injection of the red bacillus of Kiel is not fol- 
lowed by the Pfeiffer phenomenon ; after a period of hypoleucocytosis 
and transient phagolysis, hyperleucocytosis and well-marked phagocytosis 
set in. The Pfeiffer phenomenon is only an episode in the struggle of 
the organism carried on by its amoeboid cells, and is not a phagocytic 
* Proc. Roy. Soc. Lonrt., lvii. (1895) pp. 439-50. 
f Arm. Inst. Pastfeur, ix. (1895) pp. 433-G1 (1 pi.). 
1895 2 p 
