30 CHEMICAL PRODUCTS OF BACTERIA. 



man and its absorption, continued through weeks and possibly years, 

 may be of marked detriment to the health. We are not as yet in 

 possession of sufficient knowledge concerning the physiological or tox- 

 icological action of the putrefactive alkaloids to render the classifi- 

 cation proposed by Brieger worthy of general adoption ; moreover, 

 the term " toxin " is quite generally, although somewhat incorrectly, 

 employed to designate those non-basic bacterial poisons for which 

 Brieger suggested the name " toxalbumin." 



All ptomains contain nitrogen as an essentiaL part of their basic 

 character. In this they resemble the vegetable alkaloids. Some of 

 them contain oxygen, while others do not. The latter correspond 

 to the volatile vegetable alkaloids, nicotin and coniin, and the former 

 correspond to the fixed alkaloids. 



The kind of ptomain formed in a given case will depend upon the 

 individual bacterium engaged in its production, the nature of the 

 material acted upon, and the conditions under which the bacterial 

 growth proceeds, such as the temperature, the amount of oxygen 

 present, and the duration of the process. For instance, Brieger 

 found that although the Eberth bacillus grows well in solutions of 

 pepton, it does not produce any ptomains ; while the same bacillus 

 growing in beef tea elaborates a poisonous alkaloid. Fitz found 

 that while the bacillus butyricus produces by its action on carbohy- 

 drates butyric acid, in glycerin it forms propylic alcohol ; and Morin 

 has detected amylic alcohol among the products of this germ. 

 Brown has shown that while the mycoderma aceti converts ethylic 

 alcohol into acetic acid, it changes propylic alcohol into propionic 

 acid, and is without effect upon methylio alcohol, primary isobutylic 

 alcohol, and amylic alcohol. Some bacteria will not multiply below 

 a given temperature ; thus, the bacillus butyricus will not grow be- 

 low 24°.' 



The influence of the presence or absence of certain chemical com- 

 pounds upon the activity of unicellular forms of life has long been 

 known to be great. Liebig and Knapp observed that the presence 

 of small quantities of the chlorids of sodium and potassium intensifies 

 the action of yeast in the decomposition of sugar, and Dubrumfaut 

 made quantitative determinations illustrating the effects of the pres- 

 ence of other salts. He found that 0.5 gram of yeast in 100 c.c. of 

 a 10 per cent, solution of su^ar decomposed within a given time 0.5 

 gram of sugar, while in another flask to which 0.5 gram of sodium 

 acid sulphate had been added, the same amount of yeast decomposed 

 0.52 gram of sugar, and the same amount of potassium sulphate in a 

 second flask increased the activity of the yeast to 0.88 gram of sugar, 

 and in a third flask potassium nitrate raised the quantity of sugar de- 

 composed to 1 gram. Pasteur divided bacteria into two classes — the 

 aerobic and the anaerobic. As these names imply, the former grow 



■ All temperatures given in this work are centigrade, unless otherwise specified. 



