Part X, 
FEEDING EXPERIMENTS. 
GUINEA PIGS MAY BE SENSITIZED BY FEEDING HORSE SERUM. 
Our work up to this point seemed to carry us very far away from 
an explanation of the cause of sudden death in man following the 
injection of horse serum. A thorough study of the literature upon 
this subject discloses the fact that almost all the unfortunate cases 
of this kind have been due to the first injection of horse serum. If, 
therefore, man may be sensitized to a toxic principle in horse serum, 
it must be by some other means than a previous injection of horse 
serum. We have seen that von Pirquet and Schick, in their studies 
on serum disease, have actually injected children at intervals of 
several weeks without any such effect as we have found upon guinea 
pigs. Further, that on numerous occasions children have been 
given successive injections of diphtheria antitoxin at intervals of 
three or four weeks for purposes of immunization. 
In casting about for another explanation it occurred to us that 
probably this action may take place through eating horse meat. We 
therefore carried on a number of feeding experiments upon guinea 
pigs. We first fed guinea pigs with normal horse serum by means 
of a stomach tube, with the following results: 
G. P. Xo. 11G. One feeding of 5 e. c. normal horse serum (Jane) into stomach. 
27 days later inoculated with 6 c. e. antitoxic horse serum (Xatl. IX. 19) into the peri- 
toneal cavity. Xo symptoms. 
G. P. Xo. 114. Four daily feedings, each of 5 c. c., same serum. 
27 days after first feeding and 23 after last, same inoculation as g. p. 116. Xo symp- 
toms. 
G. P. Xo. 112. Five daily feedings, 5 c. c. each, same serum. 
27 days after first feeding and 22 after last, same inoculation as g. p. 116. Xo symp- 
toms. 
G. P. Xo. 113. Six daily feedings, 5 c. c. each, same serum. 
27 days after first feeding and 21 after last, same inoculation as g. p. 116. Xo symp- 
toms. 
G. P. Xo. 115. Ten daily feedings, 5 c. c. each, same serum. 
27 days after first feeding and 15 after last, same inoculation as g. p. 116. Symptoms, 
recovered. 
Only one of. these five pigs showed definite and characteristic symp- 
toms following the intrastomachal administration of the horse serum. 
This pig, Xo. 115, which was sensitive to the subsequent injections 
(67) 
