Oct. 22, 1921 Flora of Corn Meal 1 83 



formers of the mesentericus group formed the majority of the bacteria 

 obtained. 



In the lots with moistm^e content decreasing toward 13 per cent there 

 was progressive reduction in the number of active species of molds. 

 Bxtensive experimentation showed clearly that Aspergillus repens was 

 the agent which formed the balls of meal loosely held together with 

 mold hyphae, which characterized meal containing barely enough 

 water to start spoilage. In another series of experiments A. flavus 

 began to be active only in samples containing about 16 per cent of water. 

 Yeasts, mucors, and Penicillia were reported by Stiles only in the sample 

 carrying about 19 per cent of water. 



During the examination of the preliminary samples in the 1920 ex- 

 periment, an effort was made to identify the groups or actual species 

 represented. As a matter of routine, inoculations were made from each 

 flask prepared for diluting plates (consisting of 5 gm. of the meal to 

 45 cc. of sterile water) into the following media: Plain milk, gelatin, 

 and litmus lactose broth. Smears were also made on Endo's agar in 

 each instance. In every case there was prompt coagulation of the milk, 

 with extrusion of whey, but no digestion of curd. Pink rings formed 

 near the surface. Gelatin was liquefied in every instance, and acid and 

 gas formed in all broth tubes. Growth in Endo's media indicated the 

 presence of Bacterium aerogenes Escherich. Further cultural studies 

 showed that Bad. aerogenes was the predominant bacterial species pres- 

 ent in all these samples. This predominance was maintained throughout 

 the series of examinations made. Microscopical examinations of smears 

 made in each case, however, showed the presence of spore-bearing bac- 

 teria, especially the mesentericus group, and micrococci of various kinds. 

 Dextrose agar tubes often contained colonies growing deep in the media, 

 indicating the presence of anaerobic bacteria. Yeasts were found in all 

 samples, their growth being largely of the mycoderma type. The plates 

 showed many mold colonies. Various mucors, species of Fusarium, 

 Aspergillus flavus, A. niger, and occasional green Penicillia were ob- 

 served. The species of molds present on the plates varied from period 

 to period and with the sample. Molds were always more numerous on 

 plates made from meal to which Fusarium and Diplodia had been added, 

 but growth on these plates did not show dominance of these particular 

 forms. 



Evidence of the effect of bolting upon the abundance of organisms 

 was furnished in the 1920 experiment by the examination of samples 

 of two series of five bags each, representing a single lot of meal, one-half 

 of which was bolted and the other half unbolted. The bolting to which 

 these samples were subjected removed a considerable part of the bran 

 but little of the germ from the meal. After one month of storage, the 

 bolted meal showed an average of 34,000 bacterial colonies and 20,000 

 mold colonies. The unbolted samples showed 108,000 bacterial colonies 



