452 DISEASES OF SWINE 



danger, but also against any outbreak of cholera that may take 

 place weeks, months, or even years later on. 



On account of the fact that the same serum was used in this 

 herd as was used in Herd Number Eleven, it makes the results in 

 the last-mentioned herd the harder to explain. It seems that either 

 there must have been some slip in the manner of giving the serum 

 in the Number 11 Herd or else the animals on that farm simply 

 were born with an unusual tendency toward cholera. 



Herd Number Fifteen. — This herd, forming the fifteenth in 

 the series of experimental injections, was located in Section 3 of 

 Union Township, close to the town of Shipley, Iowa. This farm 

 was located in close contact with infected herds, but when seen 

 on October 16, 1907, there was no evidence as yet of the presence 

 of the disease in the drove. The herd was quite a large one, con- 

 sisting of about 70 head, most of them being small summer 

 shoats. The manner of handling this herd was as follows: 



Thirty-eight small pigs, each weighing about 30 pounds, were 

 each injected with 10 c.c. of serum alone. Twelve larger shoats, 

 weighing about 60 pounds each, received 20 c.c. of the same 

 serum. Seven old sows, of about 250 pounds weight, were each 

 given 40 c.c. of the same serum plus 2 c.c. of the virus blood. 



Two old sows and 11 shoats, weighing from 30 to 60 pounds 

 each, were left as checks. 



The results of this experiment were not quite as interesting 

 as some others, as there was no sickness seen in either the un- 

 treated or treated animals. Accordingly, the conclusion must 

 be reached that no infection reached this herd at all. 



The experiment is of interest, however, in that it again gives 

 an example of a herd in which the double method of treatment 

 was used on a part of the animals without producing any bad 

 effects in the untreated animals. In this case the old sows re- 

 ceived both serum and virus, and yet we had no development of 

 cholera either in the treated or untreated shoats, and this in 

 spite of the fact that these shoats were just at the age when they 

 would be the most easy to attack by cholera. 



The argument that using the double method of treatment 

 results in spreading of infection to other animals that are not so 

 treated seems to lack proof in this series of experiments. Espe- 



