712 BACTERIA IN AIR, SOIL, WATER, AND MILK 



As to the varieties of microorganisms present in various cheeses, much 

 careful work has been done. Duclaux ^ attributed the "ripening" of 

 some of the soft cheeses to a microorganism closely related to Bacillus 

 subtilis. V. Freudenreich ^ in part substantiated this, but laid particular 

 stress upon the action of Oidium lactis, a mold, and upon several 

 varieties of yeast. Conn,' more recently, in a bacteriological study of 

 Camembert cheese, has demonstrated that the production of this cheese 

 depends upon the united action of two microorganisms, one an oidium, 

 like the Oidium lactis of Freudenreich, which is found chiefly in the 

 interior softened areas, the other a mold belonging to the penicillium 

 variety, found in a matted felt-work over the surface and penetrating 

 but a short distance. In spite of the scientific basis upon which the 

 work of these men and of others has seemed to place cheese production, 

 attempts at uniformity in cheese production have met with almost 

 insuperable obstacles because of the presence of a variety of adventi- 

 tious microorganisms which, depending in species and proportion upon 

 the local conditions under which the various cheeses have been produced, 

 have added minor characteristics of flavor which have determined 

 market value. Occasional failure of good results in cheese production * 

 is due to contamination with other chromogenic or putrefactive bacteria. 



In its relationship to the spread of infectious disease, cheese is 

 relatively unimportant except in regard to tuberculosis. Typhoid and 

 other non-spore forming pathogenic germs can not survive the condi- 

 tions existing during cheese-ripening for any length of time. Tubercle 

 bacilli, both of the human and bovine types, have been found in cheese 

 by Harrison ' and others, and Galtier has shown experimentally that 

 tubercle bacilli may remain alive and virulent in both salted and un- 

 salted cheese for as long as ten days. 



THE LACTIC-ACID BACILLI AND METCHNIKOFF'S BACTERIO- 



THERAPT 



A problem which has occupied clinical investigation for many years 

 is that of gastrointestinal autointoxication. There are a number of 

 conditions occurring in man, in which symptoms profoundly affecting 



' Duclaux, "Le Lait," Paris, 1887. 



2 V. Freudenreich, Cent. f. Bakt., II, i, 1895. 



3 Conn, Bull. Statis. Agri. Exp. Stat. 35, 1905. 

 ' Beijerinck, Koch's Jahresber, etc., 82, 189. 



» Ilarrixoii. and Galtier, quoted from Mohkr, IT. ,S. Pub. H. and Mar. IIosp. Serv., 

 ilygiene Lab. Bull. 41, 1908. 



