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One of the problems asociated with the isolation of enzymes, antigens, and other chemical constituents from bacteria is that of obtaining sufficient quantities of cells for extraction. It is requisite that the celLs be obtained in good yield and in as short an incubation period as possible in order that esentially all the cells be viable and there be a miimum of degenerative or dissociative changes occurring in the culture. There is a paucity of literature regarding factors influencing the laboratory ma3s cultivation of bacteria. Cleary ed al. (1935) utilizing a continuous flow system for bacterial growth studies concluded that physical crowding was uinimportant in restraining bacterial growth as was the formation of specific growth inhibiting substances. These workers using Ewcheichia coli as test organism suggested that growth ceases because of changes in the availability of nutrient material and energy demand. Harmsen and Kloff (1947) proposed a method for the mass cultivation of bacteria on the surface of cellophane membranes which separated the growing orgams from the circulating medium. Humfeld (1947) described a laboratory scale fermenter for submerged culture investigations incorporating agitationaeration and foam-breaking devices. The operating capacity of the fermenter ranged from 10 to 18 liters of medium and yielded 429 grams of yeast cells in 13.5 hours. Barnes and Dewey (1947) reported a method for mass culturing Shigela organisms of the Flexner group. The apparatus allowed for the shaking of two containers holding a liter of a buffered peptone medium each. A yield was reported of 4 grams per liter in 22 hours' incubation for single propagations and 3 grams per liter in 3 hours, utilizing a continuous flow process by maintaining

SOME FACTORS INFLUENCING THE LABORATORY MASS CULTIVATION OF SHIGELLA SONNEI