528 THE RELATION OF COLLOIDS AND LIPOIDS TO IMMUNITY 



elaborately graduated pipet with a central bulbous reservoir. The 

 dropping end of the instrument ends in a flattened ground base, thus 

 insuring uniformity in the size of the drops. The instrument is so 

 graduated that a fraction of a drop can be estimated. That antigen is 

 to be chosen that does not alter the drop number for normal serum by more 

 than one drop in a cubic centimeter the strongest dilution that fulfils this 

 condition being chosen. 



The Test. The patient's serum is diluted 1 : 20 with normal salt 

 solution and its drop number determined. Then take two tubes, and 

 into one place 9 c.c. of diluted serum plus 1 c.c. of antigen dilution; 

 into the other place 9 c.c. of diluted serum plus 1 c.c. of distilled water. 

 A third tube may be prepared, which should contain 9 c.c. of normal 

 serum (1 : 20) plus 1 c.c. of the same antigen dilution. A fourth tube 

 contains 9 c.c. of a known positive serum (1 : 20) from a case of cancer 

 and 1 c.c. of the antigen dilution. 



All tubes should be carefully labeled, their drop numbers determined, 

 and then placed in an incubator at 37 C. for two hours or in the water- 

 bath at 50 C. for one hour. At the end of this time they are removed, 

 allowed to cool, and the drop number of each is determined. 



The controls are first examined to show that the antigen has not 

 undergone any change. Variations of the number above one and a half 

 or two drops (as compared with the control containing distilled water in- 

 stead of antigen) are regarded as positive reactions. The increase in drops 

 is seldom greater than eight. 



TABLE 21. MIOSTAGMIN REACTION IN CANCER 



Other Methods for Preparing Antigens. Various methods for pre- 

 paring antigen and conducting the test are to be found in the literature, 

 and it is extremely difficult to arrive at a correct conclusion as to which 

 is the best method for preparing antigen. Among these methods for 



