101 



days in the thermostat, or there is rapid and well-marked 

 haemolysis. 



That these points (with one small modification — see p. 196) 

 together constitute the essential and complete characteristics of 

 the group „Pfeiffer's bacillus" in the case of the bacterial flora 

 coming from man (which of course does not exclude the fact 

 that other characters may be valuable), will appear from 1 the 

 following investigations of these conditions and the others men- 

 tioned on pp. 68 — 70 as well as a number of other reactions. 



The Haemoglobinophilic Character of Pfeiffer's bacillus. 



By „haemoglobinophilia", — the character which has given 

 the name to the whole group that interests us here, — it 

 must be understood that it is not specially the substance hae- 

 moglobin which is necessary for the growth of the bacteria. 

 On the contrary those authors (Thalhimer (1,2), Aguliion & 

 Legroux, Oi.sen (3), Tehada, Davis (6), Thjotta & Avery (1,2)), 

 who have examined the growth of Pfeiffer's bacillus on agar 

 containing „pure" crystallised haemoglobin, have found that 

 it was very little, if at all, active in this respect. (That it can 

 be made active in various ways, will be later referred to). It 

 has also been shown that the media which afford the richest 

 growth of Pfeiffer's bacillus, are those which do not contain 

 any actual haemoglobin at all, but only the different deriva- 

 tives of it, the chemical nature of which it has hitherto been 

 impossible to determine with any degree of certainty. 



That Pfeiffer's bacillus is haemoglobinophilic therefore 

 means that it can grow on certain media which in themselves 

 are unable to cause growth, when either red blood corpuscles 

 or suitable transformation products of these are added. 



A thorough analysis of the statements in the literature on 

 the growth of Pfeiffer's bacillus without „haemoglobin" * would 

 be a rather prolix task and it is unnecessary for the investiga- 

 tion we are engaged upon. Only the following points will be 

 mentioned: 



* „Haemoglobin" in inverted commas is used in the following 

 pages as a common term for red blood cells and all such products 

 of them that make possible the growth of Pfeiffer's bacillus and 

 other bacteria with similar nutritive requirements. 



