380 Mr. J. Henderson- Smith. Increase in the [Mar. 26 ? 



No lysis was produced by 0'35 c.c. of the 5 -hours sample without immune- 

 body ; nor by 0*04 c.c. of the immune-body without the normal serum. 



In this case, then, 0*3 c.c. of the serum, withdrawn 20 minutes after 

 bleeding, was required to produce total lysis ; but with the successive samples 

 the amount required steadily decreased, until of the serum which had remained 

 five hours in contact with the clot 0*08 c.c. was sufficient. The amount of 

 complement contained in the later sample, or at least its activity, must be 

 more than three times as great as that of the complement in the earliest 

 sample. It increased steadily for five hours, and then began to diminish 

 (decreasing afterwards till it eventually disappeared). 



This example is typical. In all the experiments (seven) done with normal 

 rabbit's serum and ox corpuscles, a similar increase in the complement has been 

 observed. The amount of the increase varies, but as a rule it is to double, 

 sometimes to three times, the quantity found in the first sample. The time 

 during which increase occurs also varies. The longest time observed was 

 14 hours ; but this is exceptional, and in most cases the rise is complete in 

 five to seven hours. The same phenomenon occurs when, instead of ox 

 corpuscles and the appropriate immune-body, horse corpuscles are used with 

 immune-body from rabbits treated with injections of horse corpuscles. When 

 normal guinea-pig serum is used instead of rabbit serum to supply the 

 complement for either ox or horse corpuscles (with appropriate immune-body 

 from rabbit), the same increase to about double the amount is found. The 

 duration of the increase, however, is shorter, extending to two to four hours. 

 (In one of six experiments with guinea-pig serum the rise was very slight, and 

 complete in one and a-half hours.) 



It may be suggested that this increase in the complementing-power is only 

 apparently a change in the serum, and that the change really occurs in the 

 red corpuscles used as the reagent. In the interval between the examination 

 of the first and last samples the red cells may become more sensitive, and so 

 give a false appearance of increased power in the serum. This, however, 

 cannot be the explanation of the facts observed. The red corpuscles were 

 kept in the cold room (about 3° C.) till immediately before use, and were 

 always fresh. Under these conditions they do not become perceptibly more 

 sensitive within so short a time as seven to eight hours, when tested with 

 other lytic bodies, such as bacterial hemolysins and chemical reagents. 

 Further, the results, described later, obtained with immune sera prove that 

 no such change as is here suggested occurs in the corpuscles used. 



It was of interest to determine whether this change in the complement- 

 content of serum occurs even when the serum is removed from the clot, or 

 takes place only when it remains in contact with the clot. This was 



