1907.] Further Studies of Gastrotoxic Serum. 537 



animal showed the usual patches of necrosis in its stomach. Normal guinea- 

 pig's serum is itself able to protect an animal to a slight extent (fig. 2). 



2. Examination in vitro. — The examination was conducted from two points 

 of view : — 



(a) To find out whether the tissues of an immune animal were as susceptible 

 to the gastrotoxin as were those of a normal animal. 



(b) To ascertain what protective power the serum of the immune animal 

 possessed with regard to preventing the action of gastrotoxin in vitro. 



(a) Action upon the Tissues of an Immune Animal : Blood Corpuscles. — The 

 gastrotoxic hemolysin dissolves the red corpuscles of an immune animal to 

 exactly the same degree as it does those of a normal guinea-pig. 



Proteid Solutions. — The stomach proteid, intestine proteid, and even the 

 blood serum of the immune animal are all precipitated by the gastrotoxic 

 serum. 



Stomach Cells. — The same action is seen upon the immune cells as upon the 

 normal cells, namely, more or less clearing of the cells. 



In the case of several other poisons it has been proved that the tissues of 

 the immunised animal are still acted upon by the poison. 



(b) Protective Power of the Serum in vitro. — The protective serum was, in 

 all cases, heated to put the complement out of action. 



Hemolysin. — Haemolysis is completely prevented by the immune serum. 



The immune serum obtained from an animal after four injections prevents 

 haemolysis to some extent. After eight injections it has more power. After 

 11 injections 0'5 c.c. serum completely prevented any haemolysis occurring 

 in any of the tubes. (Haemolytic strength of the serum used : — 0"25 c.c. 

 serum completely dissolved 1 c.c. 5-per-cent. suspension of guinea-pig's 

 corpuscles.) 



Probably smaller amounts than this would suffice. The experiments were 

 only made, however, to demonstrate the presence of an anti-haemolysin. 



Precipitin. — I have not been able to show the presence of any anti- 

 precipitin. The serum of an immune animal, on being added to the gastro- 

 toxin in sufficient amount to dissolve any precipitate that forms, fails to 

 prevent the precipitation of stomach-cell proteid. 



Action on the Gastric Cells. — The changes in the cells are not sufficiently 

 definite for any very accurate determinations to be made, but my impression is 

 that the cells are as much acted upon, whether the immune serum is present 

 or not. This point must, therefore, for the present be left an open question. 



Anti-precipitins have been described, but my results fail to confirm such 

 observations. 



Anti-haemolysins have, of course, been recognised for a long while. 



