BACTERIAL CELLULAR SUBSTANCE 63 



within the domain of this work, it may be well to mention 

 the results of a few investigations. W. Smith 1 found that 

 many bacilli, including the colon, decolorize methylene 

 blue, sodium indigo sulphate, litmus, etc. He concluded 

 that this reducing action is common to all bacteria, both 

 aerobic and anaerobic; that the velocity of reduction 

 depends upon the number of bacteria and the temperature; 

 that it is a function of the bacterial plasma, and that the 

 reducing substance does not diffuse into the culture medium, 

 but that the cell retains this property for a time after 

 death. Klett, 2 testing this reducing action of bacteria on 

 sodium silicate, tellurate, and some other salts, also con- 

 cluded that the reducing agent exists in the cell, and is not 

 found among the cleavage products. Jegunow 3 showed 

 that hydrogen sulphide is formed by the reducing action 

 of bacteria on sulphates and on organic bodies contain- 

 ing sulphur. Sulphur bacteria oxidize hydrogen sulphide 

 and store sulphur in the form of oily spheres, which may 

 constitute as much as 90 per cent, of the cell substance. 

 This sulphur is oxidized to sulphuric acid, thus serving as 

 a source of energy in the vital processes of the bacterium. 

 The sulphuric acid is neutralized by carbonates and sepa- 

 rated as a sulphate; then by bacterial activity the sulphate 

 is reduced, thus forming a complete cycle. If the bacteria 

 can obtain no sulphur they use that stored up in their 

 cells and die in from one to two days. 



The above is a resume of the work done on the chemistry 

 of bacterial cells up to the time when our work was begun. 

 It should be clearly understood that we are not now con- 

 cerned with the cleavage products of bacteria produced in 

 the media in which they groAv. This subject is discussed in 

 Cellular Toxins by Vaughan and Novy (fourth edition, 1902). 



Moisture, Ash, and Nitrogen. Leach, 4 in studying the 

 chemistry of the cellular substance of the colon bacillus 



1 Centralbl. f. Bakteriol., 1896, xix, 181. 



2 Zeitsch. f. Hygiene, 1900, xxxiii, 137. 



3 Annuaire g6ologique et mineralogique de la Russie, 1900, ii, 157. 

 * Jour. Biol. Chem., 1906, i, 463. 



