IMMUNOLOGICAL BEHAVIOR 1 1 9 



ficient amount of the salt solution ^vas added to the filtrate to 

 bring the stilphate concentration up to 19 per cent. The precipi- 

 tate obtained was allo^\ ed to become almost dry on the filter paper 

 and was then transferred to a dialyzing bag in running ^vater. 

 After about six hours the white pasty mass became a clear brown 

 solution Avhich gradually grew turbid and later showed a white 

 precipitate. The dialysis ^vas continued for seventy-two to ninety- 

 six hotns initil all the sidphate ion had disappeared and no more 

 precipitate seemed to form. The globulin sohuion was centri- 

 fuged and the precipitate ^vas made up with physiological salt 

 soliuion to a con\enient volimie, e.g., 1/10 of the original seriun. 

 Extraneous matter ^vas removed by centriftiging, and the super- 

 natant fiuid filtered through a Berkefeld "V" candle. 



In the neiuralization experiments a constant vohnue of crtide 

 sertim and the same xolume of concentrated sertmi Avas titrated 

 against increasing amoinits of reacting factors (Method III) . As 

 is seen from Table vi, the total yield in neutralizing anti])odies 

 was from 44 to 52 per cent of that in the original serimi. The 

 concentration, as indicated by the quotient Neutralizing Units/ 

 mom. N, varied from 28 to 80 times. From these results it 

 could be also safely concltided that the neutralization of reacting 

 factors is not similar to the neutralization of endotoxins. Pro- 

 vided a stifficient concentration of netitralizing antibodies is used, 

 the active principles in doses of a ^vide range may be completely 

 neiuralized. 



Experiments on midtiple proportion netitralization of B. coli 

 reacting factors brotight oiu, hoAvever, a curious fact ilhistrated 

 below. 



.Vo. of neutralized Approximate 



Amount of ant i- 'Q. coli reacting Multiples of multiples of 



coli serum factors serum used neutralization 



0.25 c.c 50 



0.5 C.C 175 2 3.5 



1-5 c-c 350 6 7 



As may be seen, increase in the amount of sertnn used from 0.25 

 c.c. to 0.5 c.c, 0.75 c.c, and 1.5 c.c brought about 3.5, 5 and 7 

 fold increases in neiuralization, respectively, instead of expected 

 2, 3, and 6 fold increases. On the other hand, if the neutralization 

 figures obtained ^vith 0.25 c.c. are disregarded and multiples of 

 0.5 c.c. are considered, then 1.5 c.c. representing three midtiples 

 of 0.5 c.c. bring aboiU a 2-fold increase in neiuralization. The 



