Conventional Bacteriologic Technics in “Hormone” and “Vitamine” Research. ∗

Abstract

A fairly uniform bacteriologic technic is in current use for the demonstration of “hormones,” “vitamines” and “accessory growth-factors.” As a typical example of this technic, Nicolle and Césair 1 inoculated 10% broth-dilutions of specific immune serum with homologous bacteria, and invariably obtained a much more luxuriant growth in 10% homologous anti-serum than in normal or hetero-immune serum controls. From this they concluded that the specific “antibodies” in question are in reality specific “growth-stimulating hormones” for the corresponding bacteria.

In technics of this type there are numerous arbitrary experimental constants which may conceivably condition the end-result. Prominent among these arbitrary constants are the dosage, age, growth-phase and nutritional condition of the inoculum, and the time and method of reading the end-result. Most “hormone” data, for example, are recorded in terms of relative turbidity at the end of 24-hours incubation.

In order to test the reliability of this arbitrary time-factor, parallel “viable” and “total” population growth-curves were plotted for Streptococcus hemolyticus in 100 cc. beef-infusion broth and broth containing 0.1% beet juice. Typical curves thus obtained are recorded in Figure 1.

From these curves, it is seen that the conventional selection of the 24-hour turbidity (or “total” population count) as the recorded reading gives data apparently proving that beet-juice contains a powerful growth-stimulating hormone for streptococci. An arbitrary selection of the 2 to 5-day “viable” count, however, would give equally convincing evidence that beet auximone is a fairly efficient surgical antiseptic, causing premature death of 99% of the potentially “Viable” streptococci.