536 Dr. C. Bolton. [June 10, 



performing this test, in order to prevent haemolysis. My results disagree 

 with those of observers such as Deutsch (4) and others, who hold that specific 

 agglutinins are formed for the protoplasmic granules of cells, and who make 

 no mention of any precipitating action. Their position, according to my 

 experiments, is untenable. 



3. The Production of Immunity to Gastrotoxin. 



The effect of repeated injection of gastrotoxic serum is to produce 

 immunity to the gastrotoxin. 



It seemed that a determination of the results obtained from the continued 

 administration of gastrotoxin would be interesting from two points of view : — 



(1) With regard to whether chronic ulceration of the stomach could be 

 produced in this way, or whether the animal would become immune. 



(2) If the animal became immune, whether it would develop protective 

 substances in its blood against one or all of the constituents of the gastrotoxic 

 serum. In this way light would probably be thrown upon the actual cause of 

 the ulceration, whether it was of hsemorrhagic origin primarily, or due to a 

 direct action upon the gastric cells. 



Method. — The method which I have found to be the most satisfactory is the 

 intraperitoneal injection of inactive (heated to 55° C.) gastrotoxic serum. 



The injected animal was, of course, the guinea-pig, and the serum was 

 derived from rabbits immunised by injection of washed guinea-pig's stomach 

 cells. 



One injection of 5 c.c. was given each week. In order to produce a 

 satisfactory degree of immunity, 10 or 12 injections are necessary. 



In this way I have immunised 10 guinea-pigs. The immunity of these 

 animals was tested both by experiments in vivo and also in vitro. 



1. Examination in vivo : Active Immunity. — Four or five injections of the 

 serum will not protect an animal against a lethal dose (10 c.c.) of gastrotoxin, 

 which still produces necrotic patches in the stomach. 



After an animal has, however, received 10 injections (50 c.c. serum in all) 

 a lethal dose (10 c.c.) of gastrotoxin fails to produce necrotic patches in the 

 stomach of that animal (fig. 1, Plate 7). 



Passive Immunity. — The blood serum of an actively immune animal is 

 capable of conferring passive immunity upon another animal. . 



In an experiment of this kind a lethal dose (9 c.c.) of active gastrotoxic 

 serum was mixed in vitro with 6 c.c. inactive protective serum and the 

 mixture injected into a guinea-pig weighing 360 grammes. No lesion was 

 produced in the stomach. The control animal was inoculated with 9 c.c. 

 active gastrotoxic serum and 6 c.c. inactive normal guinea-pig's serum. This 



