DIPHTHEEIA. 125 



some instances weeks, after the inoculation, and was pre- 

 ceded by mariied emaciation. 



Tlie cultures first employed were seven days old ; older 

 cultures (six weeks) contain more of the poison, and the 

 symptoms appear within a few hours. la cultures espe- 

 cially rich in the poison, a small amount (from 0.2 to 2 c.c.) 

 injected under the skiu in guinea-pigs suffices to induce the 

 symptoms. Mice and rats are markedly insusceptible, but 

 succumb to large doses. 



Heating to 100° for twenty minutes renders the poison 

 inert, and a temperature of 58° maintained for two hours 

 markedly lessens its virulence. 



The poisonous substance is precipitated by absolute 

 alcohol, and is carried down mechanically on the addi- 

 tion of calcium chloride to the filtered cultures. These 

 investigators agree with Loffler that the poison belongs 

 to the enzymes. The great toxicity of this substance is 

 indicated by the statement of Roux and Yersin that 0.4 

 milligramme suffices to kill eight guinea-pigs or two rab- 

 bits, and that 2 centigrammes of the calcium chloride 

 precipitate, containing about 0.2 milligramme of the pure 

 poison, will kill a guinea-pig within four days. 



Briegee and Frankel have made a very complete 

 study of the chemical products of the Loffler bacillus. 

 They employed cultures of bouillon and peptone containing 

 from five to six per cent, of glycerin, and othei's containing 

 ten per cent, of sterile, fluid blood-serum. The latter were 

 found to be most suitable. In these the bacilli grow most 

 abundantly. In all cases they confirmed the statement of 

 Roux and Yersin that the cultures, at first alkaline, be- 

 come strongly acid, and finally again alkaline, with the 

 exception that the glycerin cultures remained acid. 



For the removal of the bacteria two methods were em- 

 ployed. First the bacilli were destroyed by heat. When 

 a temperature of 100° was employed the cultures were 

 rendered inert, but it was found that exposure for from 

 three to four hours to a temperature of 60° was sufficient 

 to destroy the germs, while the virulence of the chemical 

 products was not affected. The second method of removing 



