TABLE 2.

Inverse correlation between infection rates of Pn 14 and contaminating flora^a

Type of flora	Infection rate (%)
Pn 14	83.3	66.7	66.7	66.7	66.7	50.0	33.3	33.3	16.7	0.0
Contaminating flora	0.0	0.0	0.0	0.0	0.0	16.7	50.0	50.0	16.7	50.0

^aInfection rates are defined as in Table 1. Results were obtained on day 6 after standard challenge procedure with Pn 14. All pairs of Pn 14 and contaminating flora infection rates represent the results of a separate experiment. All groups received an identical standard histamine treatment; other conditions varied (e.g., dosage of pneumococci and intranasal priming with pneumococci). The r² for linear correlation is 0.63; the value of P is 0.0099.