MATERIAL FROM THE LIVING SUBJECT 225 



or pericardia! cavities may be removed with sterile pipettes and trans- 

 ferred temporarily to sterile test-tubes or flasks. Purulent discharges 

 are, if small in amount aspirated directly into sterile capillary pipettes ; 

 if in considerable quantity, removed to test tubes or flasks, and inocu- 

 lated as soon as practicable into suitable media. 



MATERIAL FROM THE LIVING SUBJECT. 



Blood Cultures. The organisms of septicemia may be numerous 

 or few in number in the blood stream furthermore, they may be 

 associated with specific lysins and agglutinins, as occasionally hap- 

 pens in typhoid fever. For these various reasons, experience has shown 

 that from 5 to 15 c.c. of blood, drawn aseptically, should be discharged 

 at once with aseptic precautions, into at least 100 c.c. of 0.1 per cent, 

 meat infusion dextrose broth, 1 and evenly distributed by careful agita- 

 tion. The degree of dilution attained practically renders lytic action 

 and agglutination ineffective; the enrichment of the medium by the 

 relatively large proportion of blood creates a very favorable medium 

 for the development of the organisms. 



Technic of Blood Cultures. 1. Apparatus. An all-glass syringe with 

 a platinum-iridium needle of moderately large bore is sterilized in the 

 autoclave, preferably enclosed in a large test tube. A syringe cannot 

 be sterilized for bacterial purposes by boiling in water. 



As an alternate apparatus, a 250 c.c. Ehrlenmeyer flask fitted with 

 a rubber stopper containing two glass tubes bent at right angles may 

 be used. The flask contains 100 c.c. of 0.1 dextrose meat infusion 

 broth. One tube is connected with a platinum-iridium needle by a 

 short length of rubber tubing, and the needle is protected during steril- 

 ization by a small test tube slipped over it and extending its full 

 length. The test tube is removed when the blood is to be taken. The 

 other tube is protected by a short length of rubber tubing containing 

 a small filter of absorbent cotton. Suction is applied through the 

 latter tube. It will be seen that blood may be drawn directly into 

 the broth in this apparatus, and in practice it has been found con- 

 venient to replace the rubber stopper with a sterile cotton plug after 

 the blood is mixed with the media. 



2. Collection of Blood. The skin over the median basilic vein is 

 cleansed with green soap and alcohol, dried, and sterilized by the 

 application of tincture of iodine, which is allowed to act for two to 



1 See Media. 

 15 



