These results seem to indicate that many bacteria may be utilized by tissue cells as food for growth or may contain a substance or substances stimulating cell growth or multiplication. This substance is stable and is not destroyed by heating to 100° C. or by long standing.
With Micrococcus aureus this action is often neutralized or overcome by a substance inhibitory to growth.
The nature of these substances has not yet been determined, though several attempts along this line were made by endeavoring to split the typhoid bacterial substance according to the method of Vaughan
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and testing the poisonous and non-poisonous residues separately. However, at the time too little bacterial substance was used to obtain enough end-products to be of much use, and the products so obtained prevented the plasma from coagulating. Even in the uncoagulated plasma there appeared to be an increase of cells in the cultures with the non-poisonous residue. The author hopes to be able to repeat these tests with split products at a later time when more bacterial substance is available, with the hope of obtaining more definite results.