Micrococcus. 1 1 



C. PATHOGENOUS SPECIES. 



12. M. vaccinse, Cohn (I.e., p. 161). 



Microsphcera vaccines, Cohn. 

 Cells round, '5- 

 75 fj. in diameter; 

 isolated or united in 

 chains and heaps of 

 two or more, also 



forming a ZOOglcea. Fig. 4 . a, Micrococcus vaccinat ; b, M. urea (after 

 /p- \ Cohn) ; c, M. ovatus (after Lebert). 



In fresh lymph from cow or human pocks, as also in 

 the pustules of true small-pox. 



According to many undoubted investigations, M. -vaccincE must be 

 regarded as the active element of vaccine lymph ; it is by its means that 

 the infectious principle is conveyed in cases of small-pox. By filtering 

 the lymph, the solid constituents can be separated from the fluid ; on 

 using the latter for inoculation, no effect is produced, while inoculation 

 by the former regularly excites the production of pocks. Moreover, that 

 the Micrococci, and not, as might be suggested, the lymph-cells, are the 

 effective constituents of the solid residuum, follows from the fact that 

 lymph which has been exposed to the air for some time grows gradually 

 less effective. For it begins to putrefy, and, as the process of decay 

 advances, the Micrococci disappear more and more, under the influence 

 of the putrefactive Bacteria. 



13. M. diphtheriticus, Cohn (I.e., p. 162). 



Cells oval, -3-1 p. long; single or concatenate, or forming 

 bundles and colonies of various shapes. 



On the so-called diphtheritic membranes, which are found 

 especially on the mucous surfaces of the throat, the pharynx, 

 the air-passages, etc., but also appear on those of the sexual 

 and digestive organs, as well as on wounds, etc. 



This Schizomycete is of extraordinarily great pathological importance. 

 For the disease spreads itself, from the centre of its first introduction, 

 through the lymphatic vessels and the tissue which surrounds them, 



