THE MEIOSTAGMINE REACTION 



219 



i. Extract: a malignant tumor which has not undergone degeneration 

 (or a sheep's pancreas) is cut into fine slices or small pieces. It is spread 

 out on glass plates and dried in a temperature of 37 C. The dried residue 

 is powdered and extracted with methyl alcohol in the proportion i : 4 for 

 24 hours at 50 C. The extract is filtered through a hard filter, at first 

 hot and then cold. It should be protected from the light, but should not 

 be placed in the ice-box. The dilutions cannot be preserved, but must be 

 made fresh every time, by measuring out the requisite amount of extract 

 with a dry pipette, placing it in a dry test-tube or flask, and adding the 

 required quantity of distilled water and shaking thoroughly. 



The extract is first titrated: dilutions 1 150, i 175, i :ioo, i 1125, etc., 

 are made, and to i c.cm. of each of these, 9 c.cm. of a i : 20 normal serum 

 diluted with saline are added. The mixtures are placed for two hours at 

 37 C. The number of drops to each quantity is estimated. A control 

 tube containing the same quantity of normal serum plus i c.cm. of distilled 

 water is also counted. That dilution is chosen as the working dose which 

 differs from the control tube by 3 to 5 fractions of a drop. 



The test is performed as follows: To 9 c.cm. of each serum diluted with 

 saline i : 20 is added i c.cm. of distilled water and the number of 

 drops falling from the stalagmometer is counted before and after incu- 

 bating for two hours at 37 C. or one hour at 50 C. This is used as a 

 control. To 9 c.cm. of each serum diluted i : 20 with normal saline is 

 added i c.cm. of antigen emulsion of the desired strength, e.g., dilution 

 i :i25. The number of drops in this mixture is counted only after 

 incubation. As further controls it is advisable to have several known 

 normal and tumor sera. The reaction is positive if the number of drops 

 contained in the mixture of tumor extract and tumor serum is greater by 

 at least 11/2 drops than in the controls after the incubation. 



9 c.cm. serum i /2O 



Number of drops per c.cm. 

 with i c.cm. tumor extract 



1:125 

 (after incubation) 



Number of drops per c.cm. 



with i c.cm. of distilled water 



(after incubation) 



The antigens spoil very easily. Recently, chemicals in the form of lip- 

 oids are being substituted for the specific antigen. This simplifies matters 

 greatly. In looking over the numerous publications by Ascoli and his 



1 S8+4 means 58 drops + 4 fractions of a drop. 



