COLLECTION OF SERUM 379 



a state of purity apart from the blood serum, conse- 

 quently special methods have been elaborated to per- 

 mit of their recognition. In every instance the be- 

 haviour of serum from the experimental animal, 

 which may be termed "specific" serum, is studied in 

 comparison with that of serum from an uninoculated 

 animal of the same species, and which is termed " nor- 

 mal" serum. In view of minor differences in constitu- 

 tion exhibited by the serum of various individuals 

 of the same series, it is usual to employ a mixture of 

 sera obtained from several different normal animals 

 of the same species as the inoculated animal, under the 

 term "pooled serum." The method of collecting blood 

 (e. g., from the rabbit) for serological tests is as follows : 



Collection of Serum. 



Apparatus required: 



Razor. 



Liquid soap. 



Cotton-wool. 



Lysol 2 per cent, solution, in drop bottle. 



Ether in diop bottle. 



Flat Hagedorn needles. 



Blood pipettes (Fig. 16, page 12). 



Centrifugal machine. 



Centrifuge tubes. 



Glass cutting knife. 



Bunsen flame. 



Writing diamond or grease pencil. 



METHOD. 



1. Shave the dorsal surface of the ear over the 

 course of the posterior auricular vein (see Fig. 192). 



2 . Sterilise the skin by washing with lysol. 



The lysol should be applied with sterile cotton-wool 

 and the ear vigourously rubbed, not only to remove 

 superficial scales of epithelium, but also to render the 

 ear hypersemic and the vein prominent. 



3. Remove the lysol with ether dropped from a 

 drop bottle, and allow the ether to evaporate. 



