112 LEO F. RETTGER 



With optimum conditions as to nutriment, and absence of 

 growth-inhibiting agents, the question of anaerobiosis is per- 

 haps not as important as it was once thought to be. 



So-called "bacterial lag" has its origin, in all probability, 

 in a paucity or temporary. absence of growth-stimulating sub- 

 stances in the new environment to which the organisms are 

 transferred. Penfold has shown that the size of the inoculum 

 is a factor. With larger amounts of material transferred cor- 

 responding amounts of the "intermediate bodies" are carried 

 over. When the amounts of inoculum are very small the indi- 

 vidual organisms are for a time at the mercy of the new medium, 

 the customary intermediate bodies being absent, or present in 

 such small quantities as to be of little or no assistance. The 

 same reasoning should hold in so far as enzymes are concerned. 

 We have on many occasions found that by very sparse seeding 

 of a culture medium with a vigorous proteolytic enzyme-produc- 

 ing organism an indefinite or indeed permanent lag period was 

 established, when the medium was one of definitely-known 

 chemical composition to which purified protein had been added. 



According to Penfold (1914) maximum growth presupposes 

 optimum concentration of intermediate bodies attainable by the 

 bacteria. When the bacteria cease developing, the intermediate 

 bodies diffuse out or disappear. The presence of inhibitory 

 products of metabohsm of the organisms must always be taken 

 into consideration, of course. A most satisfactory culture 

 medium, or one that will of itself practically eliminate bac- 

 terial lag, will be a medium which furnishes satisfactory sub- 

 stitutes for the intermediate bodies, in the form of amino acids 

 and perhaps amines of simple composition, and also certain 

 growth accessory substances. When such an artificial medium 

 is available our methods of enumerating and isolating bacteria 

 by the plating process will be attended with much greater success 

 than they are now. Too many individual bacteria fail to develop, 

 when planted in high dilution, for want of proper environment 

 and assimilable food, and die from inanition. 



These are problems, you say, of the bio-chemist. Quite true; 

 but the biochemist of today must be well grounded in general 



