CLINICAL EVIDENCE OF VALUE OF SERUM 435 



on October 4, 1907. At the time of making the first visit one 

 of the shoats had already died, but there was no evidence 

 of sickness in the other animals of the drove. An autopsy was 

 made on the dead shoat, which revealed the characteristic lesions 

 of hog-cholera — hemorrhages in the lungs, dark-red spots in the 

 kidneys, engorged and swollen spleen, enlarged lymphatic glands, 

 and ulceration of the large bowel. 



In outHning the method for carrying out the experiment in 

 this herd, 39 spring shoats, weighing from 40 to 60 pounds 

 each, were chosen for injection purposes. Eight shoats of about 

 the same average size were left untreated as checks. Five old 

 sows were also treated, but their litters, numbering in all 30 

 sucking pigs, were left untreated. Each of the injected shoats 

 received 20 c.c. of serum. Each of the 5 old sows injected re- 

 ceived 40 c.c. of serum. No virus was used in this experiment. 



The results of this experiment were as follows: Four of the 

 8 check shoats became sick and died. Two others showed 

 symptoms of the disease, but finally recovered, although they 

 remained in an unthrifty condition and were rendered practically 

 valueless. Two of the treated pigs died, while the remaining 

 37 remained well and thrifty. The old sows remained well, while 

 all but 4 of the sucking pigs died. 



When we stop to analyze this report, we find that there are 

 several points of interest to be derived from it : 



(1) In this herd cholera was already present, as is seen from 

 the fact that 1 shoat had already died, and the 2 treated shoats 

 which afterward sickened and died were perhaps already well 

 along in the state of incubation at the time that treatment was 

 given. Many of the other animals also were no doubt devel- 

 oping cholera at the time of treatment, and but for the use of 

 the serum the death-rate would unquestionably have been very 

 high. 



(2) The 2 animals which were left as checks and did not 

 sicken are an example of the natural immunity to the disease that 

 sometimes is met with. However, we here see how relatively 

 rare this natural immunity is, as only 2 animals of the 47 showed 

 this natural protection. 



(3) In this herd we again see an example of the extreme viru- 



