EMERY'S TECHNIC FOR WASSERMANN 



181 



2. Graduate a capillary pipette for i volume and 4 volumes. 



There is the greatest variation in the size of a drop delivered by a capillary pipette, 

 this difference in size not only occurring with varying diameters of the capillary 

 tube but with position of tube, thus a tube with i mm. diameter and held horizon- 

 tally will deliver about 16 drops of serum to the c.c. If held vertically about 32. A 

 fine capillary pipette, such as is used by Noguchi will deliver, when held vertically, 

 50 drops to the c.c., or 0.02 c.c. to the drop. It is therefore better to standardize 

 with known amounts delivered from a graduated pipette, using J-^Q c - c - as the un ^ 

 for i volume. 



FIG 50 i. Copper water bath 12X12X8 inches, (a) Thermometer to show 

 38C (b) Tubes containing antigen dilutions, (c) Tube containing hamolytic 

 system incubating along with the antigen tubes. 2. Ordinary rice cooker with copper 

 holder for test-tubes. 



3. Into each of a series of small test-tubes put 4 volumes of normal salt solution. 

 (These tubes are most conveniently made by breaking off 2^- to 3-inch lengths of 

 24-inch soft glass tubing and then fusing one end in the flame to make a small test- 

 tube.) 



Make a distinguishing mark, e.g., X, on end of tube with blue-wax pencil and i 

 this tube to hold control. Mark the other tubes I, II, III, and so on. When differ- 

 ent sera are to be tested they may be distinguished by lines either above or below, 

 or with circles; also marks with red-wax pencil may be used. 



4. Make a i to 20 dilution of stock antigen solution in salt solution. 



To Tube I add 4 volumes of i to 20 antigen, thus making 8 volumes of i to 40 



