Increase in the Complement-content of Fresh Blood-serum. 379 



rapidly centrifuged to free them from cells, and the supernatant fluid was 

 then tested. Each sample was examined separately as soon as it was 

 obtained, instead of waiting for the last sample and examining them all 

 together. The latter method was used as a control in a few cases, but the 

 interval between the taking of the first and last samples extended over 

 several hours, during which time spontaneous deterioration or other change 

 of the complement might easily occur in the earlier samples. Such a 

 change does, in fact, occur, as will be shown later, and it was necessary to 

 avoid this source of error. 



The examination of a sample was made in the following way : — A series 

 of test-tubes was prepared, and into each was measured the same amount 

 of immune-body (the necessary dose having been previously ascertained). 

 Diminishing amounts of the sample of serum were then added to the test- 

 tubes, the first tube receiving a large dose, the next a slightly smaller, the 

 third a still smaller, and so on. The volume of fluid in all the tubes was 

 then made the same by adding salt solution, and finally 4 c.c. of a 1-per-cent. 

 suspension in salt solution of ox corpuscles were added to every tube. 

 Control-tubes having been prepared, all tubes were shaken and placed in an 

 Ostwald water-bath at 37° C. After two hours the tubes were withdrawn, 

 and of the series the lowest tube, in which total haemolysis had occurred, 

 was noted. The dose of serum in this tube contained just enough comple- 

 ment to produce total haemolysis in that time. The same procedure was 

 carried out with every sample, the amounts of immune -body and red cells 

 being kept constant throughout. An example of such an experiment is 

 given below. 



Example 1. — Dose of immune-body = 0*04 c.c. ; 4 c.c. 1-per-cent. suspen- 

 sion ox red blood-corpuscles. Total = complete haemolysis. Time, two hours 

 at 37°. 



Dose of 

 serum 

 in c.c. 



Time in hours between bleeding of rabbit and withdrawal of sample. 



1. 



3*. 



5. 



0*4 total 



0-35 | 



0-3 



0*25 ! not total 



0-2 ... 

 0-15 ... 

 0-1 ... 

 0'08 ... 

 0'06 ... 

 0-05 ... 



total 



not total 



total 



not total 



total 



not total 



total 



not total 

 less 



total 



not total 



to 



not total 

 less 





