5io 



A CONTRIBUTION TO THE STUDY OF THE PRECIPITINS, 



auiouiit of diluted antiserum for each tube measured 0-5 c.c. In 

 this way it was possible to measure the small amounts of anti- 

 serum with some approach to accuracy. The quantities of the 

 interacting bodies are recorded in Table xiv. 



Tubes of 4 to 5 mm. bore were employed. Each tube contained 

 0"6 c.c. fluid. The readings of the precipitates after 48 hours are 



given in Table xv. 



Table xv. 



The results show that the amount of precipitate with fowl's 

 egg-white was 2-5 mm., greater than the precijutate with any 

 heterologous protein. It is also evident that, by testing with 

 diminishing quantities of antiserum, the differentiation is easily 

 made. Although 43 tubes were employed, including controls of 

 antiserum and saline solution, and protein and saline solution, t!ie 

 amount of dried antiserum employed was only 0'13 gin., equal to 

 1'3 c.c. fresh antiserum. The method is therefore economical 

 with material. When the quantity of heterologous i)roteia 

 interacting with 0-01 gm. dried antiserum is increased to produce 

 the maximum piecipitate, the amount of precipitate is le.ss than 

 the full precipitate for that amount of antiserum yielded by the 

 homologous protein. This is evident from the results recorded 

 in Table xvi. This table records the results of an experiment 

 similar to that recorded in Tables xiv. and xv,, tube 1, but carried 

 out with another antiserum. After 48 hours, the superfluids 

 were removed to clean tubes and treated with a second O'l c.c. 

 solution of protein. 



