LEO F. RETTGER 643 



SUBTILIS GROUP 



Members of this group are met with quite frequently, but according to the writer's 

 experience occur in small numbers only, in freshly voided feces. Spores of these or- 

 ganisms, like those of anaerobes, enter the digestive tract freely, to a large degree re- 

 sist the antagonistic forces of the intestine, and are eliminated as spores. However, 

 some investigators have regarded members of the subtilis group as common invaders 

 and sojourners in the intestine. 



YEASTS AND MOLDS 



These are found frequently, but it is doubtful if they multiply in the intestine. 

 Ordinary yeasts may resist the antagonistic forces of the digestive tract and pass 

 through more or less unharmed. Molds may do so also, but probably chiefly in the 

 ''spore" stage. 



MICROSCOPIC APPEARANCE OF GRAM STAINED SLIDES OF 

 NORMAL FECES OF ADULTS 



While there is, of course, considerable variation in the microscopic pictures pre- 

 sented by slides prepared and gram stained in the usual way, they are as a rule charac- 

 teristic and may be described briefly as follows: 



More or less formless, unorganized matter which takes the counterstain, though 

 often only faintly, may be seen. At times, however, practically the entire picture is 

 that of clearly defined micro-organisms. 



Gram negative bacteria predominate, and at times to the extent of 90 per cent 

 or more of the entire field; but as a rule the number varies beween 65 and 85 per cent, 

 and the average lies between 70 and 80 per cent. 



Of the gram positive organisms (20-30 per cent, average) the cocci are usually 

 the most numerous, and may outnumber the bacillary forms at least 2 to i. 



The large majority of the gram negative organisms are small and short and re- 

 semble Bad. coli. There is frequently an appreciable number of gram negative cocci. 

 It is quite probable that most of these are dead and partly autolyzed. Some large 

 gram negative rods may also be seen. A common occurrence is that of large (giant) 

 positive coccus and rod forms. 



Another not uncommon picture is that of fusiform gram negative or poorly stain- 

 ing rods or filaments, and of spirochetes. These may occasionally constitute a very 

 large proportion of the gram negative forms. Free spores may also be seen, but they 

 are easily overlooked and not always readily demonstrated. 



The foregoing inadequate description applies to feces of adults subsisting on the 

 usual mixed diet, including meat. The use of milk in appreciable quantities or of milk 

 sugar will very materially change the microscopic appearance of the intestinal flora, 

 and may transform it to such an extent as to change the entire character of the slide 

 toward the gram positive aciduric type. Meat and other high-protein diet exert the 

 opposite influence. 



LIFE WITHOUT BACTERIA 



Before the days of Pasteur no significance was attached to the occurrence of bac- 

 teria in the intestine. They were neither regarded as necessary nor thought to play 

 any harmful role in the so-called "normal individual." Pasteur was apparently the 



