48 
G. P. No. 229. Six c. c. antitoxic horse serum (Natl. IX. 17) injected into the peritoneal 
cavity. Symptoms; recovered. 
Previous treatment: 24 days prior, inoculated subcutaneously with t W o o o c. c - anti- 
toxic horse serum (Natl. IX. 19).] 
G. P. No. 230. Six c. c. normal horse serum (roan) injected into the peritoneal cavity. 
Symptoms; recovered. 
[Previous treatment: 45 days prior, inoculated subcutaneously with ytiob'OTT c - c - anti- 
toxic horse serum (Natl. IX. 19).] 
G. P. No. 228. Do. 
G. P. No. 232. Six c. c. antitoxic horse serum (Natl. IX. 17) injected into the peritoneal 
cavity. No symptoms. 
[Previous treatment: 24 days prior, inoculated subcutaneously with to~o~ o ~?o o c - c - anti- 
toxic horse serum (Math IX. 19).] 
G. P. No. 235. Do. 
G. P. No. 234. Six c. c. antitoxic horse serum (Natl. VIII. 18) injected into peritoneal 
cavity. No symptoms. 
[Previous treatment: 30 days prior, inoculated subcutaneously with TO o q-qq^ c. c. anti- 
toxic horse serum (Natl. IX. 19).] 
G. P. No. 233. Do. Symptoms; recovered. 
It is plain from the above series that guinea pigs may be sensi- 
tized with very small amounts of horse serum. Guinea pig No. 233 
received only to oio oo °f a c - c - the first injection and this quantity 
was sufficient to render it susceptible to a subsequent injection of 
horse serum. 
MINIMAL AMOUNT OF HORSE SERUM NECESSARY TO POISON A SUSCEPTIBLE 
GUINEA PIG. 
From the following series of guinea pigs it will be seen that the 
toxic principle must be present in exceedingly small quantities of 
horse serum. 
G. P. No. 4348. Four c. c. antitoxic horse serum (Natl. VIII. 17) injected into the perito- 
neal cavity. Dead in 30 minutes. 
[Previous treatment: 21 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5+ ¥ po antitoxic horse serum (PD 08021).] 
G. P. No. 4099. Three c. c. antitoxic horse serum (Natl. VIII. 17) injected into the perito- 
neal cavity. Dead in 15 minutes. 
[Previous treatment: 37 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
No. 7+ T jo c. **» antitoxic horse serum (Alex. 190).] 
G. P. No. 3954- Three c. c. antitoxic horse serum (Natl. VIII. 17) injected into the perito- 
neal cavity. Dead in 57 minutes. 
[Previous treatment: 51 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5 +- 3 I 0 c. c. antitoxic horse serum (Hubbert 1).] 
G. P. No. 4364. Three c. c. antitoxic horse serum (Natl. IX. 19) injected into the perito- 
neal cavity. Dead in 45 minutes. 
[Previous treatment: 30 days prior, inoculated subcucaneously with 0.22 c. c. toxine 
No. 7+3 To- c - c - antitoxic horse serum (PD 07173 ).[ 
G. P. No. 4350. Two c. c. antitoxic horse serum (Natl. VIII. 17) injected into the perito- 
neal cavity. Dead in 15 minutes. 
[Previous treatment: 21 days prior, inoculated subcutaneously with 0.139 c, c. toxine 
No. 5+44 q c. c. antitoxic horse serum (PD 08021).] 
