VACCINE-THERAPY 191 



The writer has recently had the privilege of visiting the 

 State Serum Institute at Rotterdam, and by the courtesy of 

 the Director — Dr. Poels — a very full and detailed descrip- 

 tion of the modus operandi of swine-fever serum was gone 

 into, which is briefly as follows : 



Four young pigs about eight weeks old are each injected 

 with 2-6 c.c of defibrinated virulent blood. When the 

 disease is established, they are killed and their blood 

 collected, the serum of which is used to hyper-immune an 

 adult pig. Into this pig 1 c.c. of virulent serum with 

 10 c.c. of immune serum is injected. 



virus, 100 c.c. immune serum. 

 200 c.c. 



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The pig in ali has now had 900 c.c. of immune serum, 

 and is hyper-immune. Dr. Poels emphasized the interest- 

 ing fact that pig serum can only produce antibodies 

 against swine fever, and that horse serum is quite 

 useless. The drawback to this is obvious. The pig being 

 a small animal a limited quantity of serum can only be 

 obtained at a reasonable price. 



The hyper-immune pig (such pigs, by the way, must be 

 possessed of long tails) is now bled to procure the immune 

 serum. After thoroughly disinfecting the tail and buttocks, 

 the animal is placed in a kind of stocks to keep it in a 

 fixed position. The tail is then cut at the end, and the 

 stump placed in a glass tube with a capacity of 200 c.c, 

 and 700 to 1,000 c.c. of blood collected ; seven days later 

 the operation is repeated. As a rule seven to fifteen 

 bleedings — the latter, if the tail is a long one — can be 

 obtained from one pig. The pig is then killed by bleeding, 

 and from 5 to 7 litres of serum is collected. The serum thus 



