BY H. G, CHAPMAN. 



533 



These results* show that there was no additional precipitate 

 in tubes 2 and 3, and small precipitates iu tubes 4, 5, 6, 7 and 8- 



Table ii. 



No. of tube. 



Precipitates after the addition of horse-serum. 



1 



2 



."J 



4 

 5 

 6 



7 

 8 



not tested, 

 none, 

 none. 

 0-3 mm. 

 5 mm. 

 O'.T nnn. 

 .1 nmi. 

 0"o mm. 



The maximum amount of preci[)itate is thus given by an amount 

 of homologous protein which is adequate to precipitate all (or 

 practically all) the precipitin. No further addition of protein 

 will augment the precipitate. 



Another series of secondary tubes was also prepared by 

 placing 02c.c. superfluid of each of the primary tubes in clean 

 tubes. To each was added 001 gm. dried antiserum dissolved 

 in 0"5 c.c. saline solution. These secondary tubes were read in 

 48 hours. The results are recorded in Table iii. 



Table iii. 



* The reading of tube 1 is too small, since the interaction is not complete 

 in 48 hours; compare Welsh and Chapman, Journ. of Hygiene, vi., p. 258, 

 1906. 



41 



