BACILLUS CUNICULICIDA. 313 



appear on the third day, and these under a low power 

 present the form of circular discs, with a sharp, dark 

 outline not quite regular, and of a yellow colour, lighter 

 towards the periphery. At a some- , ,, 



what later stage the dark yellowish ^ ' $^jj) 

 brown central zone and the clearer JT / ' ' . * 

 peripheral zone are often sharply , &, 

 marked off from each other, so that Fig.88. Baccillusof 

 the colony appears to consist of con- ft^J^&SSJ? 



. . , J rr ^ T . .. , (after Koch) X 700. 



centric layers. When it spreads at Blood ?f a gparrow 

 the surface, which only occurs to a showing the nuclei 



J of the red blood 



very slight extent, and does not corpuscles with 



extend further than a millimetre, SSSmtto^ 



the outline remains sharp, dark, 



and for the most part fairly circular, though often 



somewhat irregular. The colony presents a finely 



granular appearance at this stage. In the puncture In puncture 



n- ,. ,i . i ., f i ,1 v cultivation*. 



cultivations a thin deposit forms along the line of 

 puncture, and this deposit does not become confluent in 

 many places, but presents the appearance of discrete 

 spherical colonies of a somewhat transparent yellowish 

 white colour. On the surface it spreads in the form of 

 a flat and limited layer ; in stroke cultivations it forms 

 a thin layer somewhat thickened at the borders, which 

 are irregular and serrated ; here and there the line is 

 interrupted by isolated colonies. The cultivations only 

 retain their vitality for 4 or 5 weeks. 



If the minutest portion of a cultivation is inoculated inociUation on 

 into a rabbit (a prick in the cornea suffices) the body ' 

 temperature becomes elevated after an incubation period 

 of 10 to 12 hours, and the breathing becomes slow and 

 laboured ; ultimately the temperature falls below the 

 normal, and after the occurrence of some convulsive 

 attacks the animal dies 16 to 20 hours after the inocula- 

 tion. On post-mortem examination, the spleen and 

 lymphatic glands are found enlarged, and the lungs 

 present a strikingly marbled appearance ; there are no 

 extravasations of blood, and no peritonitis. The charac- 

 teristic rods are equally distributed everywhere through- 

 out the blood ; on sections of the various organs they 



