FILTRATION OF IMMUNE SERUMS. 



335 



Varying quantities of each of these portions were mixed with 100 

 lethal closes of tetanus toxin, allowed to stand in a test tube for thirty 

 minutes and were then injected under the skin of guinea pigs weighing 

 between 245 and 255 grams. 



Table I. — Unfiltered and filtered antitetanic serum mixed with tetanus toxin and 



tested on guinea pigs. 



Portion of serum. 



Quantity of— 



Result. 



Serum. 



Toxin. 







Lethal 







cc. 



doses. 







rJu 



100 



Lived. 



A 



ToViT 



100 



Lived. 

 Died. 





T5V5 



100 





TJuO 



100 



Died. 





rfo 



100 



Lived. 



V 



ToW 



100 



Lived. 

 Died. 





isVtF 



100 





tAu 



100 



Died. 





, sk 



100 



Lived. 



N 



1 lAii i 100 



Lived. 

 Died. 





I TiW 100 





1 tAtt : 100 



Died. 





r f5b 100 



Lived. 



W 



1 -«Vff 100 



Died. 

 Died. 





1 Ts'iJO 100 





1 T^re : 100 



Died. 



As is shown by the Table I the neutralizing values of these portions 

 of the serum must be considered identical. Although 0.001 cubic centi- 

 meter of portion W did not protect the guinea pig inoculated, such varia- 

 tions are entirely within the bounds of experimental error and even 

 greater differences are frequently encountered with one and the same 

 serum. Portions N and W were sterile. 



EXPERIMENT NO. II. 



To 200 cubic centimeters of antitetanic serum 800 cubic centimeters of phjsiolo- 

 gical salt solution was added. This diluted serum was divided into four portions, 

 A, V, N and W. Portion A remained unfiltered, and portions V, N and W were 

 passed through the Berkefeld filters so lettered. 



Varying quantities of these portions of serum were mixed with 100 

 lethal doses of tetanus toxin, allowed to stand for thirty minutes and 

 were then injected under the skin of guinea pigs weighing between 345 

 and 255 grams. 



91670 3 



