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



(calculated on the original weight of the moist bacterial paste), and filtered 

 through a sterile Berkefeld filter. One to three cubic centimetres of the 

 filtered solution are then dried in vacuo over sulphuric acid and weighed, so 

 as to ascertain the weight of material contained in the endotoxin solution. 

 This weight is regarded as the weight of endotoxin ; actually the endotoxin 

 is slightly less than is represented by this weight, in consequence of the 

 presence of traces of salts. The amount of endotoxin having been thus 

 ascertained, sufficient sterile - 8-per-eent. sodium chloride solution is added 

 to the filtered solution of endotoxin so as to form a 1-per-mille solution. 

 All the operations are performed aseptically, in order to obtain a sterile 

 preparation. 



The rabbits were all large healthy animals, and blood was obtained in 

 Wright's capsules from an ear vein. In all instances, the blood used as the 

 control was taken at the same time as the samples from the inoculated 

 animals, and the specimens for counting the number of bacteria ingested by 

 the polymorphonuclear leucocytes were made in the usual manner within 

 two to three hours after bleeding the animals. The leucocytes employed 

 were human leucocytes, as rabbit's leucocytes were found to be less satis- 

 factory for making the stained films, and the counts were made on 50 cells. 

 All the inoculations of endotoxin, tuberculin, and vaccine were made 

 subcutaneously in the back. 



Eesults obtained. 



A. Typhoid endotoxin. — The determination of the effect of injections of 

 typhoid endotoxin on the opsonising action of rabbit's serum is complicated 

 by the fact that agglutinins and bacteriolytic substances are formed which 

 cause agglutination and solution of the organisms (typhoid bacilli) in the 

 mixtures of serum, leucocytes, and organisms employed for preparing the 

 films with which the counts are made. The results, therefore, in this case 

 must be regarded as approximate only. The endotoxin was prepared from 

 an avirulent strain of the typhoid bacillus. Three rabbits were taken, one 

 being kept as a control, the two others each receiving a dose of 01 milligramme 

 of endotoxin. 



In addition to determining the opsonising action of the undiluted serum, 

 the effect of dilution was also studied, for Klien* s has shown that dilution 

 up to a certain point increases the opsonising action of human typhoid 

 serum. 



The following results were obtained : — 

 * 'Bull, of the Johns Hopkins Hospital,' vol. 18, Nos. 195 and 196, 1907, p. 245. 



