964 



CONTROL OF BIOLOGICAL PRODUCTS 



1/1,000 part of a milligram of pollen. Some manufacturers utilize this for expressing 

 the potency of their preparations. 



Clock' employed complement fixation tests. Control antiserum was prepared by 

 immunizing rabbits with a known, potent pollen extract. This serum served as a con- 

 trol in tests of the serum produced by the treatment of rabbits with the extracts under 

 investigation. 



Armstrong and Harrison^ studied this method and concluded that it might be 

 useful for testing the potency of fresh extracts but that reliable results were not to be 

 secured with old preparations, as old preparations might give a low titre but be quite 

 potent. Perhaps the most frequently used method is that based on the determination 

 of nitrogen in the preparation, though it is obvious that this does not certainly indi- 

 cate the activity of the material. The technique of Folin and Farmer^ is most fre- 

 quently employed. 



None of the methods discussed is regarded as sufficiently satisfactory for adoption 



as a standard procedure. 



TABLE IX 



Weight of Rabbit 



Venom (Mg. 

 per Kilo) 



Dose of Antivenin 



Result 



1 , 050 grams 



1,250 



I ,000 



1,300 



4-5 



6.75 



45 



6-75 



4 cc. 



5 cc. 

 None 



(Control) 

 5-cc. normal horse 

 serum (control) 



Survived 

 Survived 

 Dead ii| hr. 



Dead 18^ hr. 



ANTIVENIN 



The only antivenin of any importance, so far as concerns North America, is that 

 used against the bites of the Crotalidae (rattlesnakes, moccasins, copperheads). 

 These antisera may be tested in two ways: In one method, doses of the venom surely 

 fatal to experimental animals are mixed with varying amounts of the antivenin, the 

 mixture allowed to stand a short time and then injected into test animals — as in tests 

 with antitoxins. Obviously this gives Httle indication of the therapeutic value of the 

 serum when we consider the great rapidity with which snake venom acts upon animals. 

 American administrative authorities have therefore insisted that an antivenin should 

 be capable of influencing the action of the poison when injected after the test dose of 

 poison. Consequently the tests are conducted in this manner. The protocol shown 

 in Table IX gives the results of a test of an antivenin against certainly fatal doses of 

 the venom of the North American rattlesnake. The venom was given intramuscular- 

 ly, and the antivenin about twenty minutes later by the subcutaneous route. It is 

 obvious that if one wished to determine more accurately the minimum curative dose 

 of the antivenin, smaller quantities than were used in this test would have to be em- 

 ployed. 



■ Clock, R. O.: J. Infect. Dis., 22, 80-82. 1918. 



2 Armstrong, Charles, and Harrison, W. T.: Fub. Health Rep., 40, 1466. July 10, 1925. 



3 F'olin, Otto, and Farmer, Chester J.: "A New Method for the Determination of Total Nitrogen 

 in Urine," J . Biol. Clieni., 11, 493-501. 1912. 



