250 



derivates arc required in the medium. All the strains appear 

 to react in the same manner towards the form of ,, haemoglo- 

 bin" supplied to them. Thus they grow poorly on blood agar 

 with intact blood corpuscles and abundantly on agar with heated 

 or pepsin-digested blood. Different preparations of haemolysed 

 blood can give growth of very dissimilar intensity. But all 

 the strains go together, so that when for example any one 

 strain gave a particularly good growth (for that strain) on 

 a certain medium, it was the same with all the other strains 

 inoculated simultaneously. 



The lowest haemoglobin concentration which would support 

 growth was about the same for all the strains examined. 



It is therefore not only the dependence on „haemoglobin", 

 but also the special nature of that dependence which is common 

 to the group. 



This character persists practically unaltered even after a 

 long period of cultivation. 



(h). On suitable nutritive media growth proceeds rapidly 

 so that isolated colonies are always visible after 24 hours' 

 incubation at 37°. 



(i). All the strains (at any rate with the technique used) 

 proved to be decidedly aerobic. 



(j). No difference could be shown to exist with regard 

 to the oplimum hydrogen ion concentration of the medium 1 for 

 growth. 



(k). The minimum temperature at which growth took place 

 lay between 20° and 25°. 



(1). The cultures were killed by drying for 24 hours (under 

 further detailed experimental conditions). 



(m). Surface cultures were killed by remaining 5 weeks 

 in the cold room without being subcultured. 



(n). On blood agar (even with the addition of pepsin- 

 digested blood which increased the growth considerably) no 

 haemolysis took place during a week's incubation. 



(o). No appreciable fermentation power was observed in 

 the liquid medium containing glucose employed. 



(p). Arbutin was not broken down. 



(q). No proteolytic action (for gelatine or coagulated serum) 

 was found. 



All these characters were common to all the strains exa- 

 mined. ' 



