133 



In special tests on haemoglobin-containing ascitic agar, Pneumo- 

 coccus (a strain of each of the 4 serological types), Meningococcus 

 (a spinal fluid and a throat strain, the latter not pathogenic), Gono- 

 coccus (2 strains), and Micrococcus catarrhalis, were all very active. 



It will be observed that there is no relation between the 

 growth-promoting action on the one hand, and haemolysis, 

 acid or alkali formation, and pathogenicity for man or animals, 

 on the other. Moreover such different bacteria as cocci, an- 

 thrax bacilli, and vibrios can display the same growth-promoting 

 activity. Davis (6) too was unable to demonstrate any relation 

 between the growth-promoting power of different species of 

 bacteria and their other characters. 



Let us further consider a few of these points. As will 

 be clearly seen from the table there is no relation between 

 the haemolytic power on blood agar and the symbiosis effect 

 on agar containing dissolved haemoglobin. This is not sur- 

 prising, for as soon as the haemoglobin is brought into solu- 

 tion there can be no longer any question of haemolysis, that 

 is to say, liberation of haemoglobin from the red blood cor- 

 puscles. But it might be expected that other factors are at 

 work on blood agar. As mentioned on p. 119 some authors 

 have found that the symbiosis effect on this medium was 

 exclusively associated with haemolysis, while others found that 

 the „V" substance, which is independent of haemolysis, was 

 the deciding factor here. My experience agrees with the latter 

 finding. The 6 bacteria named below were inoculated in a 

 symbiosis test with a culture of Pfeiffer's bacillus on blood 

 agar and on agar with a little dissolved haemoglobin. 



