BACTERIOLOGY AND ITS RELATION TO OTHER SCIENCES 111 



ion concentration, preferably Pjj = 7.6, high concentration of 

 amino acids, and the presence of certain special '^ growth hor- 

 mones." The importance of blood and other animal tissues is 

 emphasized, but it is claimed that sterilization of the medium 

 by heat does not destroy the hormones which favor the growth 

 of the gonococcus. 



Gordon, Hine and Flack (1916) call attention to the special 

 growth-stimulating properties of pea flour and of wheat germ 

 extract. The former favored early growth better than the 

 germ extract, while the wheat germ extract had the more favor- 

 able influence on the longevity of the meningococcus. Agar 

 containing pea flour extract deteriorated on autoclaving. The 

 vitamins were not precipitated by alcohol. 



Here is a field that is full of promise to the student of bacterial 

 nutrition. That it is fraught with difficulties, some of them 

 perhaps insurmountable, cannot be denied. Not only is there 

 need of improved methods of cultivation in so far as the more 

 difficultly grown bacteria are concerned, as for example the 

 highly specialized parasitic or pathogenic organisms, but a 

 thorough revision all along the line is of great importance. 



The isolation and the enumeration of bacteria by the usual 

 plate method have their serious defects, in spite of the marvelous 

 progress in bacteriology which the method of isolation on solid 

 media devised by Koch in 1880 stimulated. And in no field is 

 the deficiency felt more keenly than in the isolation and study 

 of the anaerobes. It may be said, in fact, that there is as yet 

 no accepted method of enumerating anaerobic organisms, let 

 alone the question of isolation. The difficulty encountered is 

 not merely one of complete anaerobiosis, but fundamentally 

 one of nutrition. The somewhat recent methods of cultiva- 

 tion advocated by Tarozzi, (1905) Calderini (1909) and others, 

 strongly support this contention, though the interpretations or 

 explanations of the influence of the pieces of fresh tissues in 

 ordinary bouillon, by the open tube method, have never been 

 clarifying. Is not the favorable influence on the anaerobes one 

 of chemical or physiological stimulation by the pecuHar growth- 

 stimulating substances which certain animal tissues possess? 



