LEUCOTOXINS. 297 



Following technic similar to that employed by 

 Landsteiner, von Dungern obtained a cytotoxic 

 serum for ciliated epithelium of the trachea. The 

 cells disintegrated in the peritoneal cavity of the 

 immunized animal, but not in that of the normal 

 animal. This serum also proved to be hemolytic 

 in spite of the fact that no erythrocytes were in- 

 cluded in the injections. That the receptors which 

 characterize ciliated epithelium are widely distrib- 

 uted is shown by the fact that immunization with 

 cow's milk causes the formation of a cytolytic 

 serum for the tracheal epithelium of the cow. 



Leucotoxic, lymphotoxic or lymphatotoxic 

 serums are prepared by immunization with ex- 

 udates which are rich in leucocytes, or with the 

 emulsions of lymphoid organs: lymph glands, 

 spleen, bone marrow. Metchnikoff prepared the 

 first serum of this nature by the injection of the 

 spleen of rats into guinea-pigs. Leucotoxic serums 

 are toxic, not only for leucocytes, but also for red 

 corpuscles and endothelial cells. When injected 

 into the peritoneal cavity the endothelium is 

 thrown off, and when given subcutaneously the 

 capillary endothelium is attacked, with the result 

 that blood escapes to form a large hematoma. The 

 action of the serum on leucocytes may be observed 

 in vitro. The mononuclear cell's are often more 

 susceptible than the polymorphonuclears, although 

 this depends somewhat on the animals and the 

 particular organ used for immunization. The cells 

 lose their motility, the cytoplasm becomes trans- 

 parent, and swells to form a large clear vesicle, 

 which appears to be surrounded by a sharp, thin 

 membrane. The cell contents may be discharged 

 or entirely liquefied, the nucleus alone being rec- 



