82 BACTERIAL POISONS OF INFECTIOUS DISEASES. 



and some sodium acetate, then neutralized with acetic acid. An ex- 

 cess of picric acid was then added and then rendered acid with 

 acetic acid. To the filtrate alcohol was added and the precipitate 

 thus formed was redissolved and reprecipitated. The precipitate was 

 biuret-free and possessed all the properties of nucleic acids. On 

 heating with mineral acids, it did not reduce Fehling solution. It 

 was again redissolved in water by the aid of some alcohol, the solution 

 was then rendered acid with acetic acid, and the copper salt of the 

 nucleic acid obtained as above." 



By this method Levene obtained from samples of tubercle bacilli 

 grown on different culture media, nucieinic acids which varied in 

 phosphorus content from 6.58 to 13.9 per cent. The same investi- 

 gator obtained a glycogen-like substance from the tubercle bacillus. 

 This gives an opalescent solution, which on the addition of iodin 

 colors similarly to glycogen. On being heated with mineral acids 

 it reduces Fehling solution. The method of obtaining this carbohy- 

 drate is given as follows : " The bacilli were treated as described 

 above for the separation of nucleic acid. The picric acid filtrate 

 was then treated with alcohol. The precipitate thus formed con- 

 sisted of nucleic acid and glycogen. The acid can be removed 

 on addition of a solution of cupric chlorid. The copper compound 

 of the glycogen remains in solution and from the latter it can be 

 precipitated by the addition of alcohol. The copper compound 

 thus obtained is dissolved in water, the solution is acidulated 

 with hydrochloric acid until the solution reacts acid to congo, and 

 the glycogen is then precipitated with alcohol. Should the precipi- 

 tate still contain some copper, the latter can be removed by repeat- 

 ing the last operations." 



Koch's first announcement concerning tuberculin awakened great 

 activity in the study of the chemistry of the bacillus of this disease. 

 Maffucci found that cultures, when grown upon glycerin or blood 

 serum for from one to six months, and then sterilized by being re- 

 peatedly heated to from 65° to 70°, produced in guinea-pigs, when 

 employed subcutaneously, a progressive marasmus, which terminated 

 fatally within from fourteen days to six months. He also found that 

 eggs inoculated with sterilized cultures of the chicken tuberculosis 

 bacillus produced young which were feeble and soon died of emacia- 

 tion. In neither the guinea-pigs nor chickens could he find any 

 tubercles. Crookshank and Herroun reported the isolation of a 

 ptomai'n and an albumose not only from artificial cultures of the 

 bacillus, but also from bovine tuberculous tissue. Both of these 

 bodies were said to cause an elevation of temperature in tuberculous, 

 and a depression in healthy animals. Zuelzer reported the isolation 

 of a poisonous ptomain from agar cultures of the bacillus tuberculo- 

 sis. The injection of one eg. or less of this substance subcutaneously 

 in rabbits or guinea-pigs caused, after from three to five minutes. 



