BACTERIAL INVASION 



217 



of young rabbits. When the anaphylaxis-like symp- 

 toms occurred within three minutes, shortly followed 

 by death, the results were considered positive, whereas 

 very slight convulsions, followed by recovery, or 

 death after 24 hours or a week, were regarded as nega- 

 tive. 



This decision appears to be legitimate, since very 

 slight shock followed by rapid recovery frequently 

 follows the injection of many substances; and the de- 

 layed death was usually found to be due to a gener- 

 alized infection which obviously could not take place 

 within the brief time necessary for attainment of the 

 positive results following the injections. 



The results obtained in this experiment are sum- 

 marized in Table XIII below. The column headed 

 Dilution refers to the dilution of the stock suspen- 

 sions of the various extracts which were mixed with 

 the B. colt culture as described above. 



The plus sign denotes the appearance of distinct anaphylactic like symp- 

 toms within 3 minutes followed by death while the minus sign d^-notes that 

 the animals showed but slight convulsions and subsequent recovery. 



As a control upon these experiments it was found 

 that double the amount of B. colt culture or of the 

 various extracts employed could be injected singly 

 without the onset of any untoward symptoms. Since, 



