Oct. 22, I92I Flora of Corn Meal 185 



of McHargue. It has been possible, however, to go farther and indicate 

 more clearly the groups of organisms regularly present and to record 

 the conditions under which certain of them become active factors in 

 spoilage. 



Routine mass or dilution cultures show that certain molds are recov- 

 erable from practically all samples of meal. Among these are Rhizopus 

 nigricans Ehrenberg and some of the mucors which frequently overgrow 

 plate cultures within two days of incubation, although they probably 

 are present only in spore form in the meal. Syncephalastrum, belonging 

 to the same group, is not uncommon. Aspergillus flavus and A. niger 

 are only occasionally visible factors in the infection of the unground 

 grains, but they always appear as rapidly growing colonies in the mass 

 or dilution cultures made. The brown masses of A. tamari Kita are 

 commonly found with A. flavus. A. fumigatus Fres. and A. terreus Thorn. 

 are frequently present but are quickly overgrown by the more active 

 species already mentioned. A. repens, though practically always pres- 

 ent, can be found only by careful search in the presence of these rapidly 

 growing forms. 



Several strains of Penicillium are found in meal cultures. Peniciilia 

 of the group with submerged orange mycelia and of the Citromyces group 

 are probably most common. Penicillium expansum Link is reported by 

 McHargue. P. oxalicum. Thom and Currie is found in many samples of 

 meal, but rarely in miscellaneous cultural work. Strains related to 

 P. luteum Zukal and P. purpurogenum O. Stoll are frequently present but 

 usually indicate soil contamination rather than active growth in the corn 

 or meal. One sample of corn rotted by a member of this series has been 

 examined, but the conditions shown clearly indicated that the product had 

 contained high percentages of moisture at the time the rotting occurred. 



Colonies of Fusarium develop from almost every sample of meal. 

 Infections of this group are so abundant that conidia or grains of meal 

 containing living hyphae are rarely absent. Cladosporium and Alter- 

 naria are frequently found but represent spore contamination rather than 

 infection. The other organisms observed in culture from time to time 

 appear to represent excessive contaminations with spores due to unfavor- 

 able conditions in the handling of the product, or, in certain species, to 

 actual infection of the grain locally by the mold. 



The bacteria found in the fresh samples here considered were pre- 

 dominantly Bacterium aerogenes. Certain other organisms have been 

 regularly obtained in culture. When the necessary moisture is present, 

 souring is so characteristic of the product that Round and Gore (7) found 

 the addition of 3 per cent of fresh meal an adequate starter to insure the 

 dominance of lactic acid fermentation in potato silage. Lacto-bacilli 

 were present in four of the nine lots reported in Table I. According to 

 unpublished records in the Microbiological Laboratory, Round found 

 organisms of this group abundant also in fresh meal, but occasionally 



