Abstract
L-forms were produced by growing a smooth strain of H. pertussis on BG glycerine agar. Both forms were inoculated intranasally into mice, and the mice killed and autopsied at various time intervals. Examination of Giemsa-stained prepns. of lung tissue and peritoneal fluid showed that transformation from one form to the other had occurred in vivo. L-forms appeared to be more numerous in immunized mice, suggesting that this transformation may be stimulated by factors involved in resistance.