214 BIOLOGY AND TECHNIQUE 



infusion broth. At least six glucose-agar tubes should be melted 

 and immersed in water at 45 C. Before the blood is mixed with 

 the medium, the agar should be cooled to 41 in order that bacteria, 

 if present, may not be injured by the heat. The blood is added to 

 the tubes in varying quantities, ranging from 0.25 to 1 c.c. each, 

 in order that different degrees of concentration may be obtained. 

 Mixing is accomplished by the usual dipping and rotary motion, 

 the formation of air-bubbles being thus avoided. The mouth of 

 each test tube should be passed through the flame before pouring 

 the contents into the plates. Three flasks of glucose broth, contain- 

 ing 100 to 150 c.c. of fluid each, should be inoculated with varying 

 quantities of blood at least one of the flasks containing the blood 

 in high dilution. The most stringent care in the withdrawal and 

 replacement of the cotton stoppers should be exercised. 5 The writers 

 have found it convenient to use, in place of one of these flasks, one 

 containing, in addition to the glucose, 1 gm. of powdered calcium 

 carbonate. This insures neutrality, permitting pneumococci or 

 streptococci, which are sensitive to acid, to develop and retain their 

 vitality. 



In making blood cultures from typhoid patients, Buxton and 

 Coleman 6 have obtained excellent results by the use of pure ox-bile 

 containing ten per cent of glycerin and two per cent of pepton in 

 flasks. The writers have had 110 difficulty in obtaining typhoid 

 cultures by the use of slightly acid meat-extract broth in flasks 

 containing 200 or more c.c. to which comparatively little blood has 

 been transferred. The failure of a proper blood culture service in 

 most hospitals is due, we believe, to the fact that blood cultures 

 are taken by the interne staff, and worked out by the bacteriologist. 

 It is of the utmost importance, in our opinion, that a single individual 

 should be responsible for the entire examination from beginning to 

 end. This is to avoid the great possibility of contamination in blood 

 culture work. 



ANAEROBIC BLOOD CULTURES. These cultures may be taken by 

 mixing blood in deep tubes with glucose-ascitic agar, covering with 

 albolene and putting into Novy jars. 



In estimating the results of a blood culture, the exclusion of 



5 Small Florence flasks are preferable to the Erlenmeyer flasks usually employed, 

 ^Buxton and Coleman, Am. Jour, of Med. Sci., 1907. 





