MALIGNANT CEDEMA. 



221 



Rods from 3 to 3' 5 /x long and 1 to 1"1 fj, wide ; they mostly lie 

 in pairs, and then appear to be double this length. The rods are 

 rounded at their ends, and form threads which are sometimes straight, 

 but more commonly curved. In stained preparations they have a 

 somewhat granular appearance. They are motile, possessing flagella, 

 and form spores. The bacilli are distinguished from anthrax bacilli 

 by their being somewhat thinner, by their rounded ends, and by their 

 motility. Moreover, anthrax bacilli never appear as threads in fresh 

 blood, and are differently distributed throughout the body. They 

 are anaerobic, and can be cultivated on blood serum and on neutral 

 solution of Liebig's meat extract in an atmosphere of carbonic acid. 

 By embedding material containing bacilli in nutrient agar-agar 



\v 



Fig. 103. Bacilli of Malignant CEdema x 950. From the subcutaneous tissue 

 of a guinea-pig. (Baumgakten. ) 



and nutrient gelatine, characteristic cultivations are obtained. The 

 following process may be adopted to obtain a pure cultivation. A 

 mouse inoculated subcutaneously with dust, as a rule, dies in one 

 to two days. It is then pinned out, back uppermost, on a slab of 

 wood, and the hail- singed with a Paquelin's cautery from one hind 

 leg up to the neck, across the latter, and down again to the opposite 

 hind leg. Following the cauterised line, the skin is cut through with 

 sterilised scissors, and the flap turned back and pinned out of the 

 way. With curved scissors little pieces of the subcutaneous 

 (Edematous tissue, in the neighbourhood of the inoculated spot, are 

 cut out, and sunk with a platinum needle in a 1 per cent, nutrient 

 agar-agar, or 5 per cent, nutrient gelatine. Fragments of tissue may 

 also be embedded by the method already described for anaerobic 

 bacteria. 



