538 



PATHOGENIC MICROORGANISMS 



upon agar, the surface of which had been smeared with a few drops of 

 blood taken sterile from the finger. Hemoglobin separated from the 

 red blood cells was found to be quite as efficient as whole blood. This 

 method of Pfeiffer is still the one most frequently employed for isolation 

 and cultivation. Whole blood taken from the finger may be either 

 smeared over the surface of slants or plates, or mixed with the melted 

 meat-infusion agar. In isolating from sputum, only that secretion should 

 be used which is coughed up from the bronchi and is uncontaminated 

 by microorganisms from the mouth. It may be washed in sterile water 

 or bouillon before transplantation, to remove the mouth flora adhe- 



FIG. 113. BACILLUS INFLUENZA. Smear from sputum. (After Heim.) 



rent to the outer surface of the little clumps of pus. The blood of 

 pigeons or that of rabbits may be substituted for human blood. The 

 former seems to be the more favorable of the two and even more so than 

 human blood. Pigeons may be easily bled for this purpose from the 

 large veins under the wing. Huber * has succeeded in "cultivating in- 

 fluenza bacilli upon media containing a soluble hemoglobin derivative 

 known as hematogen. This substance,- however, offers some difficulties 

 to sterilization and is not so favorable as whole blood. The absence 

 of oxyhemoglobin from the hematogen, however, is theoretically im- 

 portant in that it shows that hemoglobin is suitable for the growth 



1 Huber, Zeit. f. Hyg., xv, 1893. 



