280 THE BACILLUS OF BLUE PUS 



a medium containing 2 per cent, glucose is used, and the same result is obtained 

 with white of egg. 



No pigment at all is formed in broth containing 5-6 per cent, of glucose, or when 

 the bacillus is grown on the serum of immunized animals. 



Gessard was successful in producing strains of the bacillus some of which 

 secreted the green pigment, and others pyocyanine. Wasserzug grew the 

 bacillus on slightly acid media and found that it had altogether lost its 

 power of pigment production. Charrin obtained a similar result by sub- 

 culturing in broth and incubating the cultures at 42 C. 



Melanogenie variety. Cassin and Gessard studied a strain of the bacillus pyo- 

 cyaneus which when sown in broth produced in the first instance the ordinary pigment 

 but later a dark brown and finally a black pigment. Cultures on potato formed a 

 deep brown layer which soon turned black. This production of black pigment was 

 found to be possible only when tyrosin was present in the media. In a " mineral " 

 medium such as the following : 



Ammonium succinate, - 1 gram 



Sodium phosphate, - 

 Magnesium sulphate, 

 Calcium chloride (crystals), 

 Water, .... 



1 



2 '5 grams. 

 1-25 



1000 



this bacillus produces no black pigment, the growth having all the characteristics 

 of an ordinary bacillus pyocyaneus ; but by adding 0'5 per cent, of tyrosin to the 

 medium a rose colour is at first produced which later becomes a deep brown. 



2. Toxins. 



Filtered cultures of the bacillus pyocyaneus inoculated in sufficient quantity 

 into rabbits either cause death with all the symptoms of the acute experi- 

 mental disease or lead to cachexia and paralysis which may also terminate 

 fatally. 



Wassermann obtained a very toxic product by incubating broth cultures 

 for 40 days and then sterilizing them by leaving them to stand under toluol 

 for a week. These cultures killed guinea-pigs in doses of 0*5 c.c. when 

 inoculated intra-peritoneally. 



The toxicity of the cultures is not due to pyocyanine but to certain other 

 substances, some of which are volatile, easily destroyed and have merely a 

 transitory action, while others are non-volatile. The non- volatile products 

 may be divided into two groups ; those of the first group the most toxic 

 are precipitated by alcohol, the others are soluble in alcohol (Arnaud and 

 Charrin). 



If injected into the veins of a rabbit the products of the bacillus pyocyaneus 

 rapidly lead to the death of the animal without an incubation period. This absence 

 of an incubation period is to be referred chiefly to the action of the volatile con- 

 stituents which are not a part of the true toxins. 



Pyocyanolysin. Cultures in neutral peptone-broth, 7-30 days old, filtered 

 or killed by toluol or heat (15 minutes at 60 C.), have a powerful hsemolytic 

 action on freshly denbrinated ox, sheep and rabbit blood (Bulloch and Hunter). 



Cultures 3-4 weeks old are the best for demonstrating these properties. 

 The cultures are strongly alkaline in reaction. 



Pyocyanolysin withstands high temperatures. The hsemolytic property 

 is not destroyed by heating cultures at 100 C. for 15 minutes, and it is also 

 said to be unchanged by heating at 120 C. for 30 minutes (Weingeroff, and 

 Breymann). 



3. Vaccination Serum therapy. 



If an average dose of a culture be inoculated beneath the skin of a rabbit 

 the animal suffers no harm. Rabbits can be immunized by inoculating them 



