The existence of bactericidal substances in the serum of the blood—the alexins of Buchner—has recently been questioned by Baumgarten and others who would refer the microbicidal action of the serum to osmotic disturbances and plasmolysis of the bacterial cell, caused by the salt present in the serum. In reply, Buchner1 points out that bacteria perish in salt solutions, distilled water, etc., principally because of the lack of nourishment. Active serum added to reliable and good culture-media may destroy bacteria inoculated on such media; serum loses this action when heated to 55 C., when placed in the ice-box, and even when left at the room temperature; and then it becomes a good medium for bacteria. Hence blood-serum must contain distinctly bactericidal substances, and Buchner does not hesitate to advocate the treatment of local infections by means of increased supply of blood to the part.
Buchner holds that the blood is