STUDIES ON THE SERUM OF VACCINATED ANIMALS. 23 



spleen contain irregular vibrios which are stained in places, and of a 

 reddish or violet tinge; this evidences the chemical alterations that 

 these vibrios have undergone. In the heart's blood half an hour 

 after injection there are a few phagocytes containing intact and 

 well colored vibrios. A culture from the heart on agar showed a 

 few colonies ; cultures from the liver and especially from the spleen 

 were rich in organisms. 



(c) A half culture injected into the jugular of an immunized guinea- 

 pig (480 grams). The dose was so large that the animal died in 

 4 minutes with symptoms of asphyxia. It is well shown, however, 

 in preparations from the blood taken at death that phagocytosis 

 was already present. 



When the number of bacteria injected into the circulation is not 

 too large the blood soon becomes sterile, but the organs still contain 

 living vibrios that grow well on agar.* The number of leucocytes 

 in the blood is decreased during this same period. The phenomena 

 following injection of cholera vibrios into the circulation are quite 

 similar, then, to those obtained under the same conditions with other 

 pathogenic micro-organisms] the infecting organisms are taken up by 

 the phagocytes and carried by them to the internal organs, where they 

 multiply. Immunity against cholera is dependent, then, on the 

 same mechanism as immunity against other infections. 



Phagocytic activity is apparently not easily inhibited, since the 

 accumulation of the organism in the internal organs and the dis- 

 appearance of leucocytes from the blood may be noted even in 

 chloroformed animals. Chloroform anesthesia then, sufficient to 

 deaden the nervous centers, has no effect on the activity of phag- 

 ocytes. 



EXPERIMENT 4. Vaccinated guinea-pig "A," weight 400 grams; 

 the animal was well anesthetized, so that all reflexes were lost. 

 Five minutes later one-sixth of a culture of the vibrio from Eastern 

 Prussia was injected into the jugular. The anesthetic was con- 

 tinued; the animal died after 20 minutes, as too much chloroform 

 was given. The leucocyte count had fallen from 13,000 to 4300. 

 The heart's blood was sterile, whereas the extract from liver, spleen 

 and lungs gave positive cultures. 



* Vibrios that have been in contact with bactericidal substances frequently 

 fail to grow in gelatin, although they still grow in agar. 



