May 29. 1916 Clear and Sterilized Anti-Hog-Cholera Serum 335 



at least, in swelling, followed by necrosis of tissue and the formation of 

 suppurating abscesses at the sites of injection. The extracts of the 

 scarlet runner bean (P. multiflorus) and of the pink kidney bean (P. vul- 

 garis) are both intensely irritating, v.'hile extracts of the common white 

 navy bean {P. vulgaris) are entirely lacking in this irritating property. 

 While both the scarlet runner and the kidney bean are very powerful 

 agglutinants, they have been rejected, at least temporarily, and extracts 

 of the common white navy bean have been used exclusively in our later 

 work. 



Very minute amounts of the extracts of the navy bean serve to agglu- 

 tinate large quantities of defibrinated hog's blood ; and when such agglu- 

 tinated blood is centrifugalized, the red cells pack together and form a 

 rather stiff jelly-like mass in the tube. With a precipitating force of 

 about 1 ,700 times gravity about 50 per cent of serum may be separated 

 in 15 minutes. The serum is clear and may be readily poured from the 

 tube. 



In order to secure a greater yield of serum and a more firmly packed 

 clot of red corpuscles, we find that the addition of a small quantity of 

 sodium chlorid is very effective. The addition of i per cent of sodium 

 chlorid to defibrinated hog's blood after agglutination from the addition 

 of bean extract has begun will increase the yield of serum from 50 per 

 cent without the salt to 70 per cent when the salt is added. 



Considerable experimental work has led to the adoption of certain 

 conditions of work as being most favorable to the production of the maxi- 

 mum amount of clear serum from defibrinated hog's blood. While 

 experience may later show that some changes in procedure are desirable, 

 it seems best to describe here the exact method, which is now being 

 applied in these laboratories, of producing a clear sterile serum, heated 

 to avoid the possibility of foot-and-mouth disease infection. 



Preparation of bean extract. — One hundred gm. of coarsely ground 

 white navy beans are allowed to soak for one hour in 500 c. c. of distilled 

 water, with occasional stirring. The pulp is strained through cheese- 

 cloth or cotton and mixed with powdered kieselguhr and filtered until 

 clear. A filter of paper pulp mixed with some kieselguhr has been found 

 to be efficient. The clear filtered extract is passed through a bacteria- 

 proof filter of infusorial earth. 



Preparation of defibrinated blood for centrifugalizing. — To 

 each 100 c. c. of the cool defibrinated blood add i c. c. of the sterile 

 bean extract and stir to secure a uniform mixture. Allow the mixture 

 to stand until agglutination is clearly evident. This can be determined 

 by examining a small amount in a glass or tube. Agglutination is usually 

 apparent within five minutes after adding the bean extract. There should 

 then be added i gm. of finely powdered sodium chlorid. The salt is 

 stirred in until dissolved, and the mixture of defibrinated blood, bean 

 extract, and salt is allowed to stand for about 15 minutes. 

 36290°— 16 4 



