102 



That Pfeiffer's bacillus is not absolutely haemoglobino- 

 philic, but under certain conditions can grow in media not 

 containing haemoglobin or its derivatives, has hitherto only 

 been proved by Thjotta & Avery (2) who cultivated it in 

 Usciiinsky's fluid -f- raw potato, and by Rivers (4) who used an 

 inorganic salt mixture with the addition of glycerin, ammonium 

 lactate, asparagin, tryptophan, egg and yeast extract. 



AH the other authors who have reported growth on media 

 with the addition of other substances than „haemoglobin" have 

 employed peptone broth or peptone broth-agar as substratum. 

 As broth and usually peptone also are prepared from meat 

 which commonly contains some blood and also the special 

 muscle haemoglobin (Morner), it cannot be excluded that pep- 

 tone broth may contain haemoglobin derivatives which under 

 certain conditions may be of importance for the growth of 

 Pfeiffer's bacillus, in spite of the fact that there is a general 

 consensus of opinion that this microbe (and other bacteria 

 with similar nutritive requirements) in pure culture, can- 

 not grow on ordinary peptone broth agar. It should 

 be emphasized that the applicability of this characteristic will 

 naturally not be interfered with, even if the future should 

 prove that „haemoglobin" may be replaced by quite other 

 substances to a still greater extent than hitherto. 



The failure to grow on ordinary agar can only be taken 

 as a constant character when the culture of Pfeiffer's bacillus 

 is pure. In the presence of other bacteria, — or more gene- 

 rally, other organisms, e. g. yeast cells or pieces of tissue of 

 the higher plants or animals which have never been contamina- 

 ted, growth may take place on ordinary agar or other media, 

 which otherwise would not support it. In many cases this can 

 be explained on the ground that the media contained a sufficient 

 amount of haemoglobin derivatives in such a form that they 

 do not produce growth without the further addition of the 

 „activaling" substances mentioned. This point will be further 

 discussed under the heading „Symbiosis Phenomenon". 



That some authors (Riciiter, Nastiukow' (1,2), Cantani 

 (2), and others) have obtained a growth of Pfeiffer's bacillus, 

 on agar containing bile or yolk of egg, may perhaps be explained 

 by assuming these products include bodies which are closely 

 allied to haemoglobin (the bile pigments, as is well known, 



