68 
of horse serum, had received ten feedings of 5 c. c. each of normal 
horse serum daily. In view of the fact, however, that exceedingly 
small quantities ( T oohoo c. c.) of horse serum is sometimes suffi- 
cient to sensitize a guinea pig, it seemed to us that feeding animals 
with a stomach tube might cause slight abrasions, resulting in absorp- 
tion, so that pigs fed in this manner might really be sensitized 
through minute wounds of the mucous membrane. 
We therefore used another series of pigs and fed the animals with- 
out using artificial means. As guinea pigs will not drink horse serum, 
we found it necessary to dry the serum, reduce it to powder, and 
then mix it with ground carrots. In this way they took the serum 
unknowingly with their food. By this means definite amounts of 
the horse serum may be given and the quantity given to each animal 
accurately controlled. Half a gram of the dried normal horse serum 
was thus fed to each pig, which was afterwards tested for susceptibility, 
as follows: 
G. P. No. 4551. Fed 0.5 gm. dried normal horse serum daily from March 15 to 28. Injected 
March 28 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. IX. 19), 13 days 
from first and 0 days from last feeding. Symptoms; recovered. 
G. P. No. 245. Fed 0.5 gm. dried normal horse serum daily from March 15 to 28. Injected 
March 28 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. IX. 18), 13 days 
from first and 0 days from last feeding. No symptoms. 
G. P. No. 4581. Fed 0.5 gm. dried normal horse serum daily from March 15 to 29. Injected 
April 5 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. VIII. 18), 21 days 
from first and 7 days from last feeding. Symptoms; recovered. 
G. P. No. 4540. Fed 0.5 gm. dried normal horse serum daily from March 15 to 31. Injected 
April 6 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. VIII. 18), 21 days 
from first and 6 days from last feeding. Symptoms; recovered. 
G. P. No. 4546. Do. 
G. P. No. 4575. Fed 0.5 gm. dried normal horse serum daily from March 15 to April 6. 
Injected April 6 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. VIII. 
18), 21 days from first and 0 days from last feeding. Symptoms; recovered. 
G. P. No. 172. Fed 0.5 gm. dried normal horse serum daily from March 15 to April 5. 
Injected April 6 into peritoneal cavity with 6 c. c. antitoxic horse serum (Natl. VIII. 
18), 21 days from first and 1 day from last feeding. Symptoms; recovered. 
G. P. No. 173. Do. 
G. P. No. 276. Fed 0.5 gm. dried normal horse serum daily from March 15 to April 9. 
Injected April 9 into peritoneal cavity with 6 c. c: antitoxic horse serum (Natl. VIII. 
18), 25 days from first and 0 days from last feeding. Dead in 55 min. 
There is no doubt from the above experiments that guinea pigs 
may be sensitized by feeding to them horse serum. Of the nine pigs 
so fed in the above series eight reacted to subsequent injections of 
horse serum, one of these died. 
These remarkable results are not surprising when we remember 
that Uhlenhuth a showed the possibility of the intrastomachal immu- I 
a Lhlenhuth, — ; Neuer Beitrag zum spezifischen Nachweis von Eiereiweiss auf biolo- 
gischem Wege. Deut. med. Woch., Bd. 26, 1900, p. 734-735. 
