18 Prof. It. Mnir and Mr. C. H. Browning. [May 17, 



Lysis in all with 0'07 c.c., rabbit's C. 



0-6 c.c. rabbit's Cd added to each tube ; 2 hours at 37 C., then add 



A. B. C. D. 



0-065 c.c. 0-09 c.c. 0*03 c.c. Q'05 c.c. 



Rabbit's C. Guinea-pig's C. 



1 hour in incubator. 



Add to each the test amount of red corpuscles treated with IB. 



The result is that complete lysis of all the added corpuscles occurs. 

 This shows that at most not more than a fifth of a M.H.D. of rabbit's 

 C and not more than a third of a M.H.D. of guinea-pig's C has been 



taken up. 



3. Saturation with Guinea-pig's Cd. 



Test with Guinea-pig's C. 



M.H.D. of guinea-pig's C = 0'04 c.c. (at beginning of experiment), 

 5D of IB added to 1 c.c. corpuscles, lysis with C and addition of 0'5 c.c. 

 of Cd, 2 hours at 37 C. ; 0'06 c.c. of C added, 1 hour at 37 C. ; red 

 corpuscles treated with IB added, 1 hour at 37 C. Result, 0-8 of the 

 corpuscles underwent lysis, but in a control with 0'06 c.c. of C alone 

 O'l remained undissolved. Here, accordingly, not more than about a 

 tenth of a dose of C entered into combination with the R + IB 

 molecules. 



4. Saturation with Guinea-picfs Cd. 



Test with Rabbits C. 



M.H.D. of guinea-pig's C = 0'07 c.c. 



,, rabbit's C = 0'27 c.c. 



Three tubes taken containing 1 c.c. suspension of red corpuscles, 

 treated with 6 IB. 



Lysis with 0'09 c.c. guinea-pig's C ; 1 hour in incubator. Addition 

 of 0'5 c.c., 0'75 c.c.. and 1 c.c. of guinea-pig's Cd to the several tubes; 

 2 hours in incubator. 



Addition of 0'3 c.c. rabbit's C ; 1 hour for combination. 



Addition of the test amount of corpuscles treated with IB. Result 

 in the tube with 0'5 c.c. Cd, two-thirds of the corpuscles underwent 

 lysis ; in the other tubes with 0'75 c.c. and 1 c.c. Cd, complete lysis 

 took place. Complete saturation had not occurred with 0'5 c.c. Cd, 

 but with the other amounts it had, so that at most about a tenth of a 

 dose of the rabbit's C was taken up. 



It is thus seen that it is possible to practically saturate with Cd the 

 surplus R + IB molecules after lysis. Other experiments have indicated 

 that probably a certain amount of Cd is displaced by C added after- 

 wards. But the above results show that when an excess of Cd is 

 used, the amount displaced is reduced to a trifling amount. 



