CLINICAL EVIDENCE OF VALUE OF SERUM 469 



It is highly probable that had 2 or 3 animals been left in this 

 herd to act as checks they would have developed cholera and 

 died of the disease. This would, in a way, have added interest to 

 the experiment, as it would have shown absolutely that the treat- 

 ment was protective and prevented the treated animals from 

 becoming sick. However, the experiment is a valuable one, in 

 that it serves to add to our confidence in the abihty to give the 

 simultaneous injection of serum and virus without producing any 

 harmful results. 



Herd Number Twenty. — The herd which was used as the basis 

 for the twentieth in this series of experimental injections of serum 

 was located in the southeast quarter of Section 20, Richland 

 Township, Story County, Iowa. This part of Story County is a 

 considerable distance from the herds located in Union and Grant 

 townships, which have been described in the previously mentioned 

 experiments. While not in the neighborhood of any of the infected 

 herds already mentioned, this herd was, nevertheless, in an ex- 

 posed position, as there was cholera present on a farm but a short 

 distance away. 



The animals in this herd were first seen on October 18, 1907. 

 At this time the appearance of the herd was a little suspicious. It 

 could not be said that there was any evidence of hog-cholera, and 

 yet the appearance of the animals was not the natural thrifty look 

 that is seen in healthy hogs. 



In carrying out the experiment in this herd the following plan 

 was followed: 



Twelve old hogs, which were of the average size for full-grown 

 animals, were injected with 40 c.c. each of serum and with a 2-c.c. 

 dose of virulent blood. Fifteen shoats were also injected in this 

 herd. These shoats weighed, on an average, from 50 to 120 pounds, 

 and received an injection of 20 c.c. each of serum without any 

 virulent blood. Ten sucking pigs received an injection of 10 c.c. 

 each of serum alone without any virulent blood. 



Two old sows, 2 shoats, weighing about 100 pounds each, and 6 

 sucking pigs were left as checks. 



The herd continued well until about November 10th, when the 

 untreated checks began to show indications of disease. All of the 

 untreated animals finally became sick, and they all eventually died, 



