[Vol. 9 

 3-64 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



Nutrient broth. — Peptone-beef broth testing P H 7 at 25° C. 

 produced but a faint surface growth and a slight clouding of the 

 medium in 24 hours. In 48 hours the surface growth was more 

 definite and there was a marked clouding throughout the medium, 

 there was no odor, and there was a flocculent sediment. By 

 the end of the sixth day there was a marked surface growth as 

 well as an irregular, granular growth in the upper part of the 

 medium. On agitation these readily broke up into very finely 

 divided flocculent particles. In old cultures there was a heavy 

 sediment which when agitated rose in thread-like whorls and was 

 broken up with difficulty. (One per cent of peptone was but 

 slightly better than 0.5 per cent.). 



Nutrient broth over chloroform. — As compared to growth in 

 nutrient broth in the usual atmosphere, growth in an atmosphere 

 of chloroform was much restricted, there was no surface growth 

 and only faint clouding, but the sediment was the same in amount 

 and kind. 



Nutrient broth plus alcohol. — Absolute alcohol was added to 

 nutrient broth in sufficient quantity to make solutions of 4, 5, 6, 

 7, 8, and J) per cent. There was no growth in any tube above 

 4 per cent at the end of 10 days. While this gives no exact in- 

 formation on the actual percentage of alcohol which may inhibit 

 growth, no provision having been made for the volatilization 

 of the alcohol or to account for any combination with substances 

 contained in nutrient broth, it nevertheless indicates the inhibit- 

 ing action of this substance at relatively low concentrations and 

 is quite comparable to the results obtained by others on non- 

 spore-forming organisms. 



Sodium chloride in nutrient broth. — One per cent sodium 

 chloride had no marked influence on growth; with 2 per cent 

 there was a reduction in growth and when 4 per cent was reached 

 there was no growth. In 2 and 3 per cent broth there was a 

 marked tendency to form long streamers which hung down from 

 the surface and broke up slowly when shaken. This character 

 is doubtless in the nature of a response to unfavorable, high, 

 osmotic concentrations and indicates a tendency of the organism 

 to remain united in chains and in clumps under such conditions. 



Toleration of acids. — The acids used were acetic, citric, hydro- 

 chloric, malic, phosphoric, and tartaric. Various investigators 

 have concluded that the germicidal effect of acids may be due 

 to one or more of the following factors: the hydrogen ions, the 



