330 Dr. R T. Hewlett. The Effect of the Injection of [June 5, 



there compared with the injection of an ordinary dose of staphylococcus 

 vaccine (TO c.c. = 1000 x 10 6 cocci = 0*1 milligramme). 



From this chart (IV) it will be seen that a marked rise in the opsonic 

 index results from the injection of staphylococcus endotoxin, and that the 

 rise corresponds with the dose of endotoxin given. Even the smallest dose 

 of endotoxin (0"001 milligramme, Eabbit IX), produced a considerable and 

 lasting rise in the index, a rise more marked than in the case of the vaccine 

 (Eabbit VI). 



Index 

 2-6 

 2 

 2 

 2 

 2 

 2 

 2 

 1 



11 



1-0 

 0-9 

 0-8 



RABBIT VI 



■O "3 "5 ^ 



a + oo ftJ o 

 £Q M f N 



RABBIT VII 



O TD T3 "3 



RABBIT VIII 



i t o m o 5 

 «; n * n. c£ 



o -o *o "O "a 

 x £ x = 



RABBITIX 



Chart IV. — Staphylococcus Vaccine and varying doses of Staphylococcus Endotoxin. 

 Eabbit VI received I/O c.c. (1000 X 10" cocci = - l milligramme) Staphylococcus vaccine. 

 Rabbit VII received 0'1 milligramme Staphylococcus endotoxin. 

 Rabbit VIII received 0'01 milligramme Staphylococcus endotoxin. 

 Rabbit IX received - 001 milligramme Staphylococcus endotoxin. 



A few experiments on the effect of dilution on the opsonic action of a 

 vaccine serum and of an endotoxin serum were also made, and the results 

 obtained are given in Table II. 



From Table II it will again be seen that the endotoxin produces a greater 

 rise in the opsonic index than the vaccine does. In this case dilution does 

 not affect the index in the same way as dilution of typhoid serum ; on the 

 whole the index remains much tbe same in the undiluted and the diluted 

 serum, though with dilutions of 1 in 5 and 1 in 10 more cocci are ingested 



