235 



etc. which it may be assumed, diffuses out from 1 them into the 

 medium. It seems therefore that to obtain better growth the 

 blood corpuscles must be destroyed in one way or another. 

 The simplest way of accomplishing this is to produce hae- 

 molysis (by distilled water, freezing, or the addition of sa- 

 ponin) without altering the haemoglobin. As described above 

 this method of procedure gave excellent results in my hands 

 for a long time, but at a later date liberation of the haemo- 

 globin by haemolysis only slightly increased its effect. These 

 diverging experiences from the same investigator account for 

 differences between those of other authors. Of the authors who 

 have used haemolysed blood with good effect may be named: 



DELIUS & KOLLE, KORENTSCHEWSKY, ELLERMANN, NEUFELD & 



Papamarku (1), Ruiz y Falco & Tapio, Mc Intosh, Brown & 

 Orcutt, Gosio & Missiroli, Sellards & Sturm. Some of these 

 authors expressly state that the nutritive quality of the blood 

 is enhanced by haemolysis. Davis (2), who found that haemo- 

 globin even in a dilution of 1:180000 could support a growth 

 of Pfeiffer's bacillus, made the observation with ordinary hae- 

 molysed human blood. (He says however that pigeon blood 

 was better than human blood). In opposition to this Hundes- 

 hagen was unable to notice any favourable effect from haemo- 

 lysis as such. 



We get the impression that haemolysis usually increases 

 the activity of the blood corpuscles to an appreciable extent, 

 but that the effect is not constant, and by this method we 

 seldom get a medium which produces the maximum growth 

 for Pfeiffer's bacillus. 



Among media containing haemolysed blood Thalhimer's 

 (2) agar with amorphous haemoglobin must naturally be in- 

 cluded. Carefully purified, crystallised haemoglobin, as already 

 mentioned, give practically no growth unless the aid of growth- 

 promoting bacteria is made use of, or unless it is subjected to 

 radical chemical transformations. 



4. Several of the older authors (about 1900) regarded it as 

 an established fact that a good growth of Pfeiffer's ba- 

 cillus could only be obtained in the presence of growth- 

 promoting bacteria. Quite recently also growth-promo- 

 ting bacteria, — Streptococcus, Staphylococcus, Subtilis - have 

 been inoculated on the culture plates partly to increase the 



