So 



Scientific Proceedings (47). 



These depressions are not caused by the injection of minute quan- 

 tities of ammonium sulphate per se. A recent, whole, anti- 

 pneumococcus serum, which produced rashes in humans, gave in 

 a young dog well-marked depressions and after the total injection 

 of 35 c.c. given in 7 c.c. volumes, there was a rise, 13 minutes after 

 which the dog died. This depressor substance practically dis- 

 appeared after four days standing in the ice-box. 



We have noticed a similar rise after the injection of numerous 

 6 c.c. doses of beef extracts, each of which had produced marked 

 depressions; we have however been unable to kill a dog with these 

 injections. These observations would seem to indicate that the 

 amount of depression per se within moderate limitations is not 

 so important as the recoil or loss of recoil. 



Three c.c. of nutrient peptone broth gave no depression. The 

 blood sera of a rabbit, which had 5 days previously been injected 

 with nutrient peptone broth gave splendid depressions in 6 c.c. 

 volumes. 



The blood sera of rabbits, which had been 5 days previously 

 injected with heated, sterilized, cultures of the typhoid bacillus, 

 pneumococcus, and streptococcus, gave remarkable depressions 

 in 4 c.c. volumes. 



The injection of 2Y2 c.c. of the serum of a rabbit which died 

 hours after having received 1,000 m.l.d. of tetanus toxin intra- 

 venously, gave a decided depression. 



The injection of 2Y2 cc. of the serum of a rabbit which had 3 

 hours previously received 1,000 m.l.d. of diphtheria toxin, intra- 

 venously, gave a depression. The depressor substance of both 

 of these sera practically disappeared, after standing 6 days in 

 the ice-box. 



Adrenalin chloride prevents the depression caused by the 

 tetanus depressor serum. 



Twelve m.l.d. and 15 m.l.d. of diphtheria toxin gave no reaction 

 when injected into the dog intravenously, 3 c.c. of broth containing 

 210 m.l.d. of diphtheria toxin gave a well-marked depression when 

 injected intravenously into a dog which had been sensitized 24 

 hours previously with 100 m.l.d. of diphtheria toxin. 



The blood serum of rabbits injected with 3 m.l.d. of diphtheria 

 and tetanus toxins, drawn 4 days after the injections, gave marked 

 depressions. 



