550 A CONTRIBUTIO.V TO THE STUDY OP THE PRECIPITINS, 



ing 0-5 gm. powdered seeds with 10 c.c. saline solution. The 

 extracts were filtered and divided into two parts; one part was 

 then heated to 70°C. for 4 hours and filtered, while the second 

 part was unheated. The heated extract was sterile, and the 

 tubes did not show bacterial changes for some days. The 

 unheated extract soon showed signs of putrefaction. In addition 

 to the usual controls, it was necessary to arrange, each time, a 

 series of tubes in which normal rabbit's serum interacted with 

 the extracts of the seeds. The importance of this control is 

 evident from Table xviii. 



Table xviii. 



It is seen that 11 out of the 15 seeds gave extracts which 

 yielded precipitates with normal serum. These extracts could 

 not be used for tests with antiserum. 



A series may now be recorded in which the preliminary tests 

 and controls were satisfactory. This experiment is recorded in 

 Table xix. 



The antiserum v/as prepared by the injection of extracts of the 

 seeds of Acacia pi/cnantha containing 3*0 gm. dried protein, given 



