Role of carbon dioxide in the dimorphism of Coccidioides immitis.

Converse (J. Bacteriol., 74, 106, 1957) described a procedure for the conversion of arthrospores and mycelial fragments of strain AM-11 of Coccidioides immitis to the spherule form. He used a defined medium containing Tamol "N," and reported maintenance of the spherule form the density of the culture generally increased to 4.0 to 4.5 mg per ml as determined by the dry weight of material retained by an HA Millipore membrane. Transfers were made to fresh medium after the cultures were centrifuged and the supernatant medium discarded. These cultures have