796 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The author has been able to breed from drinking-water cocci which 

 are possessed of a high degree of movement. Though almost always 

 diplococci, they sometimes appear as streptococci, and betimes as tetrads ; 

 their diameter is 1 /x. The double cocci are clearly divided by a fissure, 

 and, both in the unstained and in preparations stained with fuchsin or 

 by Gram's method, their coccus form is indisputable. Their form is 

 easily cultivated at the ordinary temperature in gelatin-agar, potato- 

 paste, &c., but does not grow at the body temperature. They liquefy 

 gelatin, but only very slowly. Though the cocci themselves seem to be 

 colourless, they always produce a rose-coloured pigment. The peculiar 

 motion with which they are endowed is easily observed in drop-culti- 

 vations. This is best seen in 5 per cent, milk-sugar-agar, wherein it is 

 kept up for several days. 



The movements are swimming in character, various in direction, and 

 of a rapidity of about 10 /^ a second. Anything which lessens the vitality 

 of the cocci diminishes the movements, and they cease altogether in 

 1 per 1000 HgClg, 5 per cent, carbolic acid, dilute sulphuric acid, or if 

 killed by heat, though the molecular movements still go on. 



These two kinds of movements can be differentiated by increasing 

 the viscosity of the fluid ; for, as this is increased, so the molecular move- 

 ments diminish. Again, the more the drops are cooled down, the more 

 the viscosity increases, until finally the Brownian movements cease 

 altogether. At this point the specific movements are still going on, and 

 only cease when the drop has become solid. 



To this fungus the author gives the name of Micrococcus agilis. 



Variability of Bacillus anthracis* — M. A. Chauveau has continued 

 his important investigations into the conversion of pathogenetic microbes. 

 He finds that by continuing the action of compressed oxygen on cultiva- 

 tions of developing Bacillus anthracis, he is able to form races or types, 

 which offer less resistance than the primitive Bacillus, and are particularly 

 sensitive to the action of the attenuating agent to which the Bacillus owes 

 its new properties. If the influence of the attenuating agent is continued, 

 the new types finally lose their power of growing when brought into con- 

 tact with it ; but so long as the Bacillus does not pass the limits of vege- 

 tability, it remains among pathogenetic agents. It is true that it loses 

 all its virulent properties, but it completely preserves the vaccinal 

 property, and preserves it almost intact during the whole period of its 

 existence. These new characters are definite, and may be easily brought 

 about by cultivation in successive generations. If we were to take 

 no account of their origin, we might regard these types by themselves as 

 forming distinct species. It is not impossible that special types of 

 Bacillus anthracis do exist in nature with properties absolutely identical 

 with those of the races which have been made in the laboratory. 



New Bovine Tubercle Bacillus.t — M. J. Courmont has found a new 

 tubercle bacillus in the pleura of an ox attacked with " pommeliere." 



The bacillus is short and broad, and consists of a clear median zone, 

 slightly constricted, and of two terminal nuclei (? spores). It is very 

 mobile, grows rapidly on all the media usually employed, and does not 

 liquefy gelatin. Cultivations were obtained at 46°, and in vacuo. It is 

 easily stained and decolorized. The tubercles of the ox, when not mixed 

 with the bacillus of Koch, gave pure cultivations straight away. 



* Comptcs Ecndus, cix. (1889; pp. .551-0. t T. c, pp. ieO-2. 



