MORPHOLOGY 563 



of the spores which are in the soil is facilitated by the numerous other 

 organisms present. 



3. Symptoms and lesions. 



The septicaemia of Pasteur runs a similar course in all animals but the 

 duration of the disease varies with the species inoculated. 



The symptoms in the guinea-pig which are typical of those seen in other 

 animals are as follows : very soon after the inoculation of a trace of a viru- 

 lent culture beneath the skin of the thigh or 

 abdomen an oedema forms at the site of in- 

 oculation ; a few hours later the animal with 

 its coat staring is found crouching in a corner 

 of its cage showing no inclination to move, 

 convulsions soon appear and death supervenes 

 often in less than 12 hours. 



When the virulence of the organism is very 

 high, the oedema is negligible and the septi 

 caemia develops very rapidly, death taking 

 place after a very few hours' illness. 



Post mortem, there is more or less oedema 

 at the site of inoculation the muscles in the ^ ^ _ The of nt 



neighbourhood are bright red and infiltrated oedema. Smear preparation from the 

 \Kr\^n Q eorrma ovnrlafn -/hilo f>io nrmnoo+iTra surface of the liver of a guinea-pig. 



with a serous exudate, wmie tne connective Carbol . blue . (Oc.n.obj.^th, Reich) 

 tissue is distended with bubbles of fetid gas 



and crepitates beneath the finger. A variable amount of almost clear serous 

 exudate is present in the peritoneal cavity : the liver is discoloured and the 

 spleen diffluent while the lungs are normal in appearance. A most disagreeable 

 smell emanates from the carcase. 



The fluid of the local oedema contains large numbers of bacilli but no 

 leucocytes. The peritoneal exudate examined under the microscope also 

 gives the appearance of a pure culture of the bacillus with numerous fila- 

 mentous forms : spores are not found in the living animal, but are formed 

 rapidly after death, especially if the carcase be kept in the incubator at a 

 temperature of 35 C. 



The bacillus of malignant oedema is very seldom found in the blood of 

 animals during life, but it enters the blood stream soon after death. If the 

 body be left in the incubator (35 C.) for a few hours and blood films be 

 then made a large number of bacilli will be found. 



SECTION II. MORPHOLOGY. 

 1. Microscopical appearance and staining reactions. 



The bacillus of malignant oedema is a rod-shaped organism measuring 

 3-15/x x O6-1/A, more slender than the anthrax bacillus, and occurring singly 

 or in chains. Chains are particularly numerous in the blood of carcases 

 kept for a few hours at 37 C. : under these conditions the bacilli form long 

 filaments (40/x) made up of unequal segments. The rods though sometimes 

 straight are more often curved and wavy ; their ends are clean cut and very 

 slightly rounded at the angles, in contrast to the ends of the anthrax bacillus 

 which are sinuous but form a right angle with the lateral surface. 



The bacillus is motile, but only under anaerobic conditions, so that the 

 centre and not the edge of the preparation should be examined. The vibrios 

 move with a slow undulating creeping movement due to flagella arranged 

 laterally on the organism. 



