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



By J. Henderson-Smith, M.B., Philip Walker Student of Pathology in the 



University of Oxford. 



(Communicated by Professor Gotch, F.R.S. Received March 26, — Read 



May 9, 1907.) 



Very soon after coagulation has occurred in blood withdrawn from the 

 vessels, serum begins to be expressed. The amount, at first small, increases 

 rapidly, and in a few hours, at room temperature, contraction of the clot is 

 practically complete. Some observations made in the course of other work 

 suggested that the composition of the serum first yielded differs from that 

 of the serum expressed later, and a special investigation of the point led 

 to the results recorded in this paper. The serum given off from the clot 

 at varying intervals of time after bleeding was tested for its content in 

 hemolytic complement. This body was selected for examination, not only 

 because it can conveniently be studied in the test-tube, but also because 

 much greater quantitative accuracy of result can be obtained with it than 

 with, for example, a bactericidal complement. In most of the experiments, 

 the serum of rabbits was tested against the red blood-corpuscles of the ox, 

 and the necessary immune-body was derived from the serum of rabbits 

 immunised by repeated injections of these corpuscles. In some instances 

 other combinations were used, as is stated later, but in every case the red 

 cells used for injection and for examination were fresh, and had been freed 

 from serum by being washed thrice in many times their bulk of isotomic 

 salt solution. The experiments fall into two groups, according as the serum 

 examined was from a normal animal or from an animal that had been 

 previously immunised. 



1. Normal Serum. 



The method adopted was as follows : — A rabbit was treated with injections 

 of ox red blood-corpuscles, and when its serum had reached a sufficiently 

 high titre, its blood was withdrawn and the serum obtained. This was then 

 heated for half an hour at 56° C. to destroy the contained complement, and 

 served as a stock of " immune-body " (by which name I shall refer to it in 

 the rest of this paper). The neck of a normal rabbit having been shaved 

 and sterilised, the large vessels of the neck were cut, and the issuing blood 

 was caught in a sterile flask. As soon as coagulation had occurred, the 

 clot was loosened from the sides of the flask by a sterile glass-rod. At 

 varying intervals of time, samples of the separating serum were taken and 



