118 



The Nature of Precipitin Reactions 



The quantity of precipitum formed remained constant up to 50 C., 

 but from 55 C. to 62" C. a marked diminution was noticed. At 63' C. 

 a further reduction occurred, and at higher temperatures the formation 

 of precipitum ceased. All solutions gave a good foam-t< 



The figures given below are the mean of two estimations in each 

 case. 



Normal undiluted ox serum fieated for 3 minutes. 



Unbeated 

 40 C. 

 46 

 60 

 65 

 M 

 57 

 68 

 69 

 M 

 61 

 63 

 63 

 64 

 M 

 66 

 67 

 68 

 69 

 70 

 75 



Precipitum 

 0262 

 0262 

 0262 

 M9 

 0225 

 0225 

 0215 

 0215 



met 



0187 

 0187 



M-7 

 0122 



Percentage 

 100 



Eemirkj 



Blight opalescence 



82 

 74 

 71 



46 

 

 

 

 

 

 

 

 



Increased opalescence 



Marked 



Opaque 



and solid 



These experiments, as far as they go, appear to indicate that an 

 antiserum can be exposed to a greater degree of heat than its 

 corresponding serum without injury, and that the precipitum-producing 

 property is completely destroyed in the latter at a lower temperature." 



The effects of filtration of Normal Kera through " stone " filters. 



" It has been already indicated that the substance of " stone " filters 

 when allowed to act on serum exerts some influence on the serum 

 exposed to it. In order to further test this point ox serum was filtered 

 through a new Berkef'dd filter, and through a new clean Chamberland 

 filter. After a certain quantity of serum had filtered through it was 

 removed, and specimens from it diluted and tested. It was found that 

 in the former case the precipitum-foi ming power was at first diminished, 



