iS QUATERCENTENARY STUDIES IN PATHOLOGY 



the finger each day for 12 days, and kept in the dark in unsealed 

 capsules. The sera thus obtained were compared with fresh serum for 

 opsonic content (in all the experiments my own washed blood corpuscles 

 were used), and the experiments on normal serum were conducted on 

 my own serum or that of healthy normal individuals. 



Cocci per leucocyte. 



Fresh serum, 2 hours old - - - 17*6 



Serum, 24 hours old - - - - i6"8 



M 48 M - . . - 15-4 



II 3 days old . . . . 14-3 



II 5 M - - - . 14-2 



II 8 II - . - . io*3 



II 10 II . - . - 8*5 



II 12 II - - . - 6'5 



Serum over 3 weeks old - - - 2*5 



Thus it is seen that there is a gradual diminution from the first day 

 onward, and that it would give quite erroneous results if we were to 

 compare sera of different ages with regard to opsonic content. 



What are the changes the serum undergoes within the first few hours 

 of its withdrawal from the body ? 



Blood was drawn from the finger at different times during the day, 

 and left exposed to daylight when all the samples were tested 

 simultaneously. 



Thus it is shown that there is a gradual increase up to about two 

 hours in the quantity of opsonin in the serum. It may be asked, 

 however, does the increase in opsonin depend on a change in the serum 

 itself, or is it due to certain substances squeezed out of the clot ? 



(382) 



