VACCINATION 567 



Post mortem examination of animals dying as the result of the intra-peri- 

 toneal inoculation of toxin shows the intestines and peritoneum to be congested 

 and the peritoneal cavity to contain a little sterile exudate. 



The addition of iodine solution seems to modify the properties of the toxin very 

 slightly. Heat, on the other hand, has a distinct effect : a temperature of 80 

 or 100 C. markedly diminishes the toxic property of cultures. 



If the toxin be kept for some time at 35 C. in diffused daylight it soon loses its 

 properties, but if stored in a closed vessel away from air and light at room temperature 

 it does not deteriorate. 



(6) The product obtained by filtering the oedematous fluid of animals dead 

 of the disease is much less toxic than the toxin prepared as above. Doses 

 of 2-10 c.c. of the filtered exudate inoculated into the peritoneal cavities of 

 guinea-pigs weighing 280-350 grams do the animals no harm. In guinea- 

 pigs weighing 300 grams doses of 15-20 c.c. produce more or less severe 

 symptoms but the animals always recover. Death only occurs when doses 

 of 30-40 c.c. are given intra-peritoneally. 



Chemio tactic properties. The toxin of the bacillus of malignant oedema 

 has negative chemiotactic properties (Besson). 



Aspirate the toxin into capillary tubes 2-3 cm. long and seal one end. Introduce 

 the tubes beneath the skin of guinea-pigs and rabbits through very small incisions 

 and after 8, 10 and 20 hours remove them and examine their contents. Although 

 control tubes containing a little of the broth used for the cultures and inserted 

 beneath the skin at the same time now contain a turbid liquid very rich in leucocytes 

 the contents of the tubes containing the toxin are clear and no leucocytes can be 

 detected on microscopical examination. It is only after 24 or 30 hours that the 

 latter contain leucocytes : this may be due either to the fact that the properties 

 of the toxin have undergone modification from their prolonged contact with the 

 living tissues or to the fact that the toxin has diffused out and been replaced by 

 lymph. 



Heating at 85 C. for 2 or 3 hours fundamentally alters the chemiotactic 

 properties of the toxin : previously negative they are now positive and 

 tubes inserted beneath the skin of guinea-pigs and rabbits quickly fill with 

 leucocytes. 



(iii) Leclainche and Morel obtained an active toxin by growing the organism 

 in Martin's broth : the culture was decanted not filtered, because the filter 

 retained a portion of the toxin. The product obtained killed rabbits in 

 doses of 5 c.c. when inoculated intra-venously. Intra-cerebrally 5-6 drops 

 produced a fatal result. 



3. Vaccination. 



Roux and Chamberland succeeded in vaccinating guinea-pigs by repeatedly 

 inoculating large doses of broth cultures heated at 110 C. for 10 minutes 

 into the peritoneal cavity. After inoculating a total quantity of 120 c.c. 

 of the heated culture on three separate occasions at intervals of 3 days the 

 animals were found to be immune. 



Immunization by the injection of increasing doses of filtered meat cultures 

 is very difficult (Besson). Most of the animals submitted to the treatment 

 died of a chronic cachexia. 



Roux and Chamberland immunized guinea-pigs by inoculating them on 

 seven or eight occasions with 1 c.c. of oedema fluid which had been filtered 

 through a porcelain bougie. 



Besson has succeeded in immunizing rabbits by repeatedly inoculating 

 them in the cellular tissue of the ear with the unaltered exudate. On the 

 first occasion ^-lih of a drop is inoculated into the extreme tip of the ear : 

 a sharp reaction occurs and the inoculated part has an erysipelatous appear- 



