GENERAL TECHNIC 



433 



stoppered with a cork or a rubber stopper is quite satisfactory (Fig. 108). 

 Vial, stopper, and needle are readily sterilized in boiling water, drained, 

 and cooled, the specimen collected, the vial tightly stoppered, and the 

 whole sent at once to the laboratory. Cotton stoppers are unsatisfac- 

 tory, as unless the tube or vial is maintained in an upright position, the 

 fluid may be absorbed. When specimens of blood are to be mailed, it 

 is better to fill a small vial than to place the same amount in a large 

 container, for in the latter case agitation through handling may result 

 in so much mechanical hemolysis taking place 

 as to render the serum unsatisfactory for use. 

 Specimens so collected may be sent for long 

 distances, even in warm weather, and undergo 

 no change. 



In collecting blood from children, or where 

 the veins are small, a proportionately smaller 

 needle may be used. In infants the cupping 

 apparatus of Blackfan is quite satisfactory (p. 

 36); frequently sufficient blood may be ob- 

 tained from a great toe. 



The specimen of blood should be kept in a 

 cold place, and the serum removed at the end 

 of twenty-four hours. Serum that is allowed 

 to remain with the clot for longer periods is 

 more likely to become anticomplementary, 

 especially if it becomes deeply tinged with 

 hemoglobin. In cases where the serum does 

 not separate the clot may be broken up gently 

 with a sterile glass rod and centrifugalized. 

 The serum should be clear and free from cor- 

 puscles. Opalescent and milky serums, ob- 

 tained during the period of digestion and from 

 nursing women, usually do not interfere with 



the reaction; bile-stained serum may at times give marked non-specific 

 fixation of complement. 



It is essential that all serums be heated at 55 C. for half an hour imme- 

 diately before the test is made. This exposure to heat somewhat diminishes 

 the reacting power of a syphilitic serum, but, as shown by Seligman and 

 Pinkus, it is a necessary procedure, for a considerable proportion of nor- 

 mal serums or those from diseases other than syphilis will react positively 

 when unheated, whereas when heated, they will give a negative reaction. 

 28 



FIG. 108 A VIAL TO 

 CONTAIN BLOOD FOR 

 THE WASSERMANN RE- 

 ACTION. 



This is an ordinary 

 glass vial fitted with a 

 rubber stopper. It holds 

 5 c.c. to the mark, and 

 is readily packed for mail- 

 ing. Never stopper with 

 cotton. A good cork stop- 

 per may be used. 



