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SUMMARY OF CURRENT RESEARCHES RELATING TO 
By these researches it became very probable that both the blue and 
the red forms belonged to a single species of bacterium, and that that 
was B. coli commune. 
The very considerable differences in shape are not, according to the 
author, contradictory of this view, since by breeding pure cultivations of 
the bacterium in bouillon containing different qualities of alkali and 
acid, he has convinced himself that these variations produce extraordi- 
nary polymorphism. The principal cause of the variable behaviour to 
stains must rather be sought in the influence of the nutrient medium, 
conditions certainly present in the intestinal canal. After that the 
reaction, the absence of oxygen, the saline constituents, and so forth, had 
been excluded, it followed that the fat normally present in the stools of 
suckling infants was the cause of this alteration in the bacteria. By 
breeding pure cultivations on buttery media (agar or gelatin) similar 
properties were imparted to bacteria as were possessed by those in 
stools : they resisted decoloration with iodine and assumed the slim 
rodlet form, like those present in the stools of suckling infants. Thus 
the variable behaviour of the bacilli in normal and clayey stools on the 
one hand, and those in slimy stools almost free of fat and watery 
evacuations on the other was explained. 
If the bacteria from butter-gelatin were sub-cultivated in the usual 
way, they again lost the resistance to the iodine solution. Yet none of 
the fat-dissolving media was able to impart this peculiarity, and the 
expectation of finding a diagnostic method for recognizing bacterial 
diseases of the alimentary tract failed, though it must be admitted that 
these researches have brought to light new and interesting peculiarities 
in B. coli commune. 
Fertilization-processes in Vibrios.* — Dr. Max Dahmen has observed 
that certain of the superficial colonies of some vibrios (V. Koch, 
Finkler-Prior, Metschnikoff, Denecke) are distinguishable into two 
varieties called a and /3 colonies. The a colony sends a prolongation 
into the (3 colony, the latter inverting itself over the extension like a 
bell-jar, so that the compound colony somewhat resembles a mushroom 
or a bell and its clapper. The a colonies seem to possess very little, and 
the (3 colonies no inclination to run together when cultivated apart, but 
when in association they unite eagerly and produce the most diverse 
appearances. The effect of the metabolic products of the a colonies is 
shown by the fact that the /3 colonies grow with extraordinary rapidity, 
and liquefy the gelatin in a corresponding manner when the latter are 
subjected to its influence. 
Both the a and (3 colonies breed fairly true, though in both single 
vibrios arise from which are developed colonies with opposite character- 
istics. From the fact that the gelatin is more quickly liquefied and 
that proliferation is more rapid, the author considers that the organisms 
have acquired new properties and that the acquisition is the result of 
the influence of other individuals of the same species. Also he thinks 
that the difference in the characters of an epidemic are to be explained 
by the differences noted in the a and (3 colonies and their mixtures, 
and would further explain the absence of severe symptoms in Petten- 
kofer and others by supposing that they took (3 cultivations. 
* Centralbl. f. Bakteriol. u. Parasitenk., xiv. (1893) pp. 43-53 figs.). 
