Production of Antisera .M) 



in the few animals I have treated by the intravenous method. Of 

 the 26 animals noted in the preceding table (p. 54) 1 1 show a loss of 

 weight, in the figures I have given, whereas the others regained their 

 weight or even greatly increased in weight. Several of those which 

 had lost weight, as recorded, had regained it when killed. Of the 

 11 that lost in weight, 3 only lost 50 70 g., 5 lost 130 220 g., a loss 

 of no great moment. On the other hand 3 lost heavily, viz. Nos. 3, 6, 

 and 14. Of these, No. 3 was treated with pig serum ; at the third 

 injection it exceeded its original weight, by the last it had fallen 

 400 g., 60 g. more being lost by the time it was killed. A greater 

 loss of weight is noticeable in Nos. 6 and 14 (treated by Mr Strangeways) 

 where the treatment was continued longer, the intervals between in- 

 jections being shorter, and in No. 6 the dosage very high. This animal 

 however gave a powerful antiserum. 



When to kill the treated Animals. 



When the animals have received usually 5 to 6 injections, and some 

 days have elapsed, it is well to draw off samples of blood and to test 

 these for precipitins. This is accomplished by shaving the ear, making 

 a small cut into a vein, and allowing the drops of blood which flow out 

 to fall into a Petri dish, which is then covered and set aside, being 

 slightly tilted. After an hour or two the serum will have separated 

 and can be tested. If it prove insufficiently powerful treatment may 

 be continued, whereas if it shows power the animal may be killed, the 

 time for killing being preferably 7 to 12 days after the last injection. 



Killing the Animals and Collecting the Antiserum. 



The animals may bo killed in a variety of ways. Uhlenhuth 

 (25, vn. 1901) chloroforms them, opens the thoracic cavity under aseptic 

 precautions; and, cutting through the beating heart, the blood is allowed 

 to flow into the thoracic cavity, whence it is removed by means of sterile 

 pipettes to suitable vessels. Others isolate the carotid, insert a sterile 

 cannula, and allow the blood to flow through it into suitable sterilized 

 vessels. 



The method I have pursued is very much simpler, and usually gives 

 quite as good results, and certainly more blood. Having shaved the 

 neck, and disinfected the skin with lysol solution, the hair on the head 

 and fore-part of the body being moistened with lysol to prevent hair 

 flying about, the animal's head is bent backward, putting the skin of 



