We may formulate the results as follows:
1. Bacillus paratyphosus in lactose-peptone-water causes a fall in the curve. The explanation of this must be left to later investigations.
2. Bacillus paratyphosus in glucose-peptone-water shows at the beginning a rise similar to that produced by coli, but a fall in the curve follows.
3. If Bacillus coli is added to a 24 hour paratyphosus lactose culture a very long latent period is obtained before the formation of acid by coli becomes apparent, presumably due to accumulated basic metabolic products.
4. If Bacillus coli is added to a 24 hour paratyphosus glucose culture the curve is not changed from the normal to any perceptible degree.
5. Bacillus coli communis and Bacillus paratyphosus in lactose in mixed cultures give a longer latent period than coli alone. The first ascending part of the curve is due to acid formation by the coli which in the beginning is dominant. Later paratyphosus dominates and causes an ultimate decline in the curve.
6. Bacillus coli communis and Bacillus paratyphosus in glucose in mixed culture behave like Bacillus paratyphosus in pure culture.
The purpose of these investigations has been for the present to show the usefulness of the method. It is hoped that by these investigations material of particular interest relating to the biochemical and physiological processes within the bacterial culture will be obtained.