On the Nature of Bacterial Lag

Abstract

(1) If B. coli be subcultured into another sample of the same medium when growing at full pace, it will continue to grow at the same pace.(2) If the maximum rate of growth be interrupted by a short application of cold, growth will recommence without lag on the temperature being raised. If the cold be long continued, lag will tend to reappear.(3) Differences in the size of inoculum have practically no effect on lag in the case of large inoculums, in the case of small ones, on the other hand, diminution of the seeding has the effect of lengthening lag, and this lengthening effect is more marked the smaller the seedings become.(4) Lowering the temperature lengthens the lag. The effect is very similar to the effect on growth.(5) The older a parent culture (within limits) the longer the lag.(6) The length of lag varies with the medium even if adaptation has been arranged for beforehand.(7) Heat-stable products in B. coli cultures on peptone water have, in the case of overnight cultures, but little effect on lag.(8) After washing the bacteria for two hours with saline in order to remove possible inhibiting agents, it was found that the lag, on subculture, still occurred and was indeed slightly longer.(9) If a peptone water culture of B. coli be centrifuged, it is found that the few bacteria remaining in the supernatant commence to grow again at a quick rate but not without a period of lag.