PRECIPITIN TEST IN CANCER 315 



add 2 c.c. of the properly diluted extract. Controls should be made up 

 with normal serums, and also the extract with a fluid corresponding to 

 that with which the tissue extract was prepared; that is, by adding to 

 100 c.c. of a 1 per cent, solution of acid sodium phosphate 5 c.c. of 5 per 

 cent, acetic acid and neutralizing with sodium carbonate. 



The precipitate forms at once, and must be viewed by transmitted 

 and not by reflected light. The practical value of the test, however, 

 has not been established. 



