52 Dr. R T. Hewlett. [Mar. 28, 



Series IV. — Inoculated with 1 c.c. of typhoid vaccine (1,000,000,000 

 bacilli) on May 21, 1909. 



Table IV. — Inoculated with Living Culture on June 18, July 7, July 21, and 

 July 28, 1909. 



Keference letter 



Date of 



Amount of 











Eesult. 



C 



June 18 



5 M.L.D.'s 



Lived. 











Fi 1 



July 7 



2 



+ Lived. 



A 







K 



5 





V 









Z 



July 21 



5 



+ Dead, July 22. 



BB 



8 



DD 





8 





KK 







+ ), 



H 





8 „ 



Lived. 



N 

 B 



July 28 



8 

 8 



+ Dead, July 22. 

 + Dead, July 29. 



HH 





8 





O 





8 



+ » » 

 111, but recovered. 



P 





8 



The controls to the animals inoculated on June 18, July 7, and July 21 

 were the same as those in Table I, and on July 28 as in Table II. 



Summary of Results obtained with Typhoid Endotoxin. — The experiments 

 detailed in Tables I, II, and III indicate that injections of 1, 01, and 

 - 01 mgrm. of typhoid endotoxin confer considerable protection against 

 subsequent injections of living typhoid bacilli. With amounts of 1 and 

 0-1 mgrm. of endotoxin the protective power was maintained for a period of 

 nearly 11 weeks. With - 01 mgrm. of endotoxin the protective power 

 appeared to be maintained for six weeks, but did not seem to be manifest 

 after eight and nine weeks ; but it is to be noted that in the two last 

 instances the test dose of typhoid bacilli was larger than that employed 

 previously. As regards the typhoid vaccine the results obtained with it 

 correspond with those obtained with the lowest dose of endotoxin, viz., 

 0'01 mgrm. 



Immunisation against the Bacillus diphtheria?. 

 The diphtheria endotoxin was prepared by growing a virulent diphtheria 

 bacillus on the surface of blood-agar for 48 hours, collecting the growth, 

 well washing twice with physiological salt solution by centrifuging in order 

 to remove adherent toxin, and grinding, etc., in the usual way. The endo- 

 toxin solution was prepared on June 17, 1909. 



