TEXT-BOOK OF BACTERIOLOGY. 281 



filled with clear liquid, having- a decided resemblance to cholera 

 bacilli. 



By resorting to the microscope the same difference will be ob- 

 served. In one case we have yellowish-brown masses, variously 

 conglomerated into thick granular or crumbling lumps seen in 

 livelj T motion with a weak magnifying power. The edge, as in 

 Finkler's colonies, is studded with a uniform border of the finest 

 radiating filaments. In the other case we see colonies strongly 

 resembling those of Koch's vibrios a liquefying funnel outlined 

 against the solid gelatin by sharp lines, at the bottom of which fun- 

 nel the bacterial growth lies as a glossy, yellowish-white heap, com- 

 posed, as it were, of small pieces of glass. 



These obvious differences might incline us to think that we did 

 not have a pure culture, but rather a mixture of two different 

 kinds. But by taking a small quantity of one or the other sort of 

 these colonies and preparing new plates, we will always see the 

 two forms reappear, being varieties of the same micro-organism 

 and differing mainly by the greater or less amount of peptonizing 

 power. Our judgment is, therefore, confirmed that the vibrio 

 Metschnikoff occupies in its culture on our artificial media an in- 

 termediate place between Koch's and Finkler's vibrio, sometimes 

 inclining more to the one or to the other, and that it is similar to 

 Deneke's vibrio as to its energy of growth. 



R. Pfeiffer (who has thoroughly investigated this subject) justly 

 points to the fact that it is easy to distinguish a pure plate cul- 

 ture of the cholera vibrio from one of the vibrio Metschnikoff, but 

 it is absolutely impossible to discern and recognize a few colonies 

 of the one among many of the other. 



This conformity of the two micro-organisms often becomes 

 manifest. The stab-culture of the. vibrio Metschnikoff in gelatin 

 exactly resembles that of the cholera vibrio, except that the latter 

 grows much more slowly, so that simultaneous inoculations can 

 easily be kept apart. 



The growth on oblique agar again reminds us of the cholera 

 bacteria; likewise the growth on potatoes, which at breeding tem- 

 perature are covered with a moderately luxuriant, yellowish-brown 

 or chocolate-colored covering. But on developing in bouillon a 

 certain difference will be noticed, inasmuch as the liquid under 

 the influence of the vibrio Metschnikoff at incubator temperature 

 becomes entirely cloudy after a very short time, assumes a grayish- 

 white color, and gradually allows only a folded thin film provided 

 with numerous wrinkles to arise on the surface, while the comma 

 bacillus keeps the culture solutions clear for a much longer time and 

 never changes them into a thick gray broth. 



