BY H. G. CHAPMAN. 



545 



principle adapted to other circumstances has been euijiloyed to 

 distinguish between closely related proteins, e.g., those of avian 

 eggs. As an example, an experiment may be considered which 

 records the interaction between an antiserum for fowl's egg- 

 white and the egg-white of the hen, duck, quail, ostrich, par- 

 tridge, and pheasant, by which the heterologous egg-whites of 

 the different eggs were clearly distinguished from the hen's egg- 

 white. The antiserum was derived from a rabbit which had 

 received six injections of egg-white containing 6'27 gm. dried 

 egg-white. When the rabbit was killed, the antiserum was dried 

 invactio over calcium chloride at37°C. At the time the experi- 

 ments were performed, the dried antiserum was over two months 

 old. For the experiment, 0-13 gm. dried antiserum was dissolved 

 in 5-2 c.c. saline solution. The antiserum was thus diluted sa 

 that 0*4 c.c. solution was equivalent to 001 gm. dried antiserum, 

 0-2 c.c. solution to 0-005 gm. antiserum, 0-08 c.c. solution to 

 0-002 gm. antiserum, 0-04 c.c. solution to 0-001 gm. antiserum, 

 and 002 c.c. solution to 0-0005 gm. antiserum. To interact with 

 the antiserum, 1 c.c. egg-white of each kind of egg was diluted 

 with 99 c.c. saline solution, and 0-1 c.c. of the solution of each 



Table xiv. 



kind of egg-white placed in each of six tubes. The antiserum 

 was measured out in quantities of six times that required for 

 each tube, and saline solution added in such quantity that the 



