Cell multiplication and phage formation of lysogenic B. megatherium cultures have been determined under various conditions and in various culture media.

1. In general, the more rapid the growth of the culture, the more phage is produced. No conditions or culture media could be found which resulted in phage production without cell growth.

2. Cultures which produce phage grow normally, provided they are shaken. If they are allowed to stand, those which are producing phage undergo lysis. Less phage is produced by these cultures than by the ones which continue to grow.

3. Cells plated from such phage-producing cultures in liquid yeast extract medium grow normally on veal infusion broth agar or tryptose phosphate broth agar, which does not support phage formation, but will not grow on yeast extract agar.

4. Any amino acid except glycine, tyrosine, valine, leucine, and lysine can serve as a nitrogen source. Aspartic acid gives the most rapid cell growth.

5. The ribose nucleic acid content is higher in those cells which produce phage.

6. The organism requires higher concentrations of Mg, Ca, Sr, or Mn to produce phage than for growth.

7. The lysogenic culture can be grown indefinitely in media containing high phosphate concentrations. No phage is produced under these conditions, but the cells produce phage again in a short time after the addition of Mg. The potential ability to produce phage, therefore, is transmitted through cell division.

8. Colonies developed from spores which have been heated to 100°C. for 5 minutes produce phage and hence, infected cells must divide.

9. No phage can be detected after lysis of the cells by lysozyme.

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