94 PROPERTIES OF KLEMOLYTIC SERA 



It is thus seen that very much more complement, about fifteen 

 times as much, passes through on the second filtration. 



EXAMPLE 2. Dose of complement before filtration . . 0-005 c.c. 

 after filtration, about 0-5 



2nd filtration. Dose of complement before filtration . 0-005 

 after filtration . . 0-005 



In this case the result is even more striking ; the filter having 

 been rendered practically permeable to complement. We then 

 tested to what extent the property of retaining complement might 

 be restored by burning the filter at a dull red heat in a hot-air 

 chamber. The filter was the one used in the last example, and after 

 being heated it was tested, with the result : 



Dose of complement before filtration . . . 0-005 c.c. 

 after filtration .... 0-04 



It is thus evident that the property of retaining comple- 

 ment has, to a certain extent, been restored by heating the 

 filter. 



We have also tested the effect of passing through the 

 filter serum which has been deprived of complement by 

 heating at 55 C. The serum used was that of the rabbit. 

 About 10 c.c. of a mixture of serum diluted with equal parts 

 of salt solution was passed through, then the effect of filtering 

 guinea-pig's complement was tested. The result obtained 

 was 



Dose of complement before filtration . . . 0-003 c.c. 

 after filtration .... 0-005 



Accordingly, more than half of the complement has passed 

 through the filter, a result which is never obtained with 

 a fresh filter. Heated serum, that is, serum deprived of 

 complement, thus removes, to a certain extent, the property 

 which a filter has of retaining complement. The effect of 

 passing egg-white through the filter was very much less 

 marked. Egg-white passes through with great difficulty, 

 requiring to be diluted with about ten volumes of salt 



