74 APPLIED IMMUNOLOGY 



tion of the culture of typhoid bacilH ; ( c ) teclmic of the 

 test. 



(a) Cpllection and Dilution of the Patient's 

 Serum. — There are several methods of collecting blood 

 from the patient, which will be given in the order 

 preferred. 



(1) By means of Wright's capsule: A piece of 

 %-inch glass tubing is drawn out to a fine capillary 

 stem at each end, leaving a portion with the original 

 calibre about 2 inches in length. One of the capillary 

 ends of the tube should be bent (see Fig. 22, B), The 



Fig. 4. — Capillary teat pipette for removal of serum from clotted specimen of blood. 



patient's blood is drawn into the curved end of the cap- 

 sule by capillar}^ attraction from a puncture of the 

 finger or lobe of the ear. When the tube is almost full, 

 the ends can be sealed in a small flame. After the 

 blood has clotted and the serum separated, a file mark 

 is made at a convenient level on the tube, which is then 

 broken, and the clear serum drawn off by means of a 

 capillary pipette (Fig. 4). Any desired dilution of 

 the serum can now readily be made by taking one drop 

 of serum from the pipette, and the required number 

 of drops of distilled water with the same pipette. The 

 dilutions usually employed in performing the Widal 



