164 APPLIED IMMUNOLOGY 



with methyl alcohol in the proportion of 1 : 4 at 50'' 

 C. for 24 hours. It is then filtered while hot, and 

 again after cooling. The serum is employed in 1 : 20 

 dilution in normal saline solution. 



In preliminary titration of the extract, decreas- 

 ing quantities, made up to 1 c.c. with distilled water, 

 are placed in tubes with 9 c.c. of 1 : 20 dilution of nor- 

 mal serum. A control is also prepared with plain 

 water and serum (without extract). These mixtures 

 are incubated at 37° C. for 2 hours, after which the 

 number of drops in each tube is noted by means of the 

 stalagmometer. For the test, the dose of extract is 

 employed which is in the tube that contains 3-5 parts 

 of a drop more than the control tube. 



The following table will illustrate the titration of 

 the extract : 



9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 

 9 c.c. normal serum (1 



20) 4- 1 c.c. extract 1 



20) + 1 c.c. extract 1 



20) + 1 c.c. extract 1 



20) + 1 c.c. extract 1 



20) + 1 c.c. extract 1 



20) + 1 c.c. extract 1 



20) + 1 c.c. extract 1 



50 

 75 

 100 

 125 

 150 

 200 

 300 



20) + 1 c.c. aqua dest. (control) 



Number of drops 

 i^Q [59 + 3 parts of a drop. 

 j-o 59+1 part of a drop. 

 o^ 59 + 1 part of a drop. 



"d!^ 59 



^ 03 1 58 + 9 parts of a drop. 



g £ 58 + 8 parts of a drop. 



^ g 58 + 8 parts of a drop. 



.J5 I 58 + 8 parts of a drop. 



In this case the dose of extract to be used in the test 

 would be 1 c.c. of the 1 : 100 dilution, which shows 

 about 3 parts of a drop more than the control. 



Before using the extract for diagnostic purposes, 

 this dose, as determined by titration, should be tested 

 for reliability with a number of known carcinomatous 



