372 



[Vol. 9 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



500 grams of washed, healthy leaves of Chaetochloa lutescens 

 and of C. viridis were boiled in distilled water for 1 hour, the 

 extract decanted, and the well-cooked leaves squeezed between 

 cheese-cloth in order to obtain a maximum amount of extract. 

 Fifteen grains of agar were added and enough water to make one 

 liter of each decoction. The growth on slants of both of these 

 decoctions was meager and no difference was detected. The ex- 

 periment indicates that between 2 different cooked decoctions, 1 

 of a resistant and the other of a susceptible plant, there was no 

 difference in growth, and it is felt that further than this no con- 

 clusion seems justified. 



Amino acids in relation to growth. — Time has not permitted 

 a thorough study of the role of amino acids in the growth of the 

 foxtail organism, but the experiment here reported is indicative 

 of a line of work that should be fully investigated. 



TABLE VII 



AMINO ACIDS IN RELATION TO GROWTH 



Solution 



(1) 0.1% tyrosine* 



(2) 0.1% tyrosine + 1.0% dextrose 



(3) 0.1% tyrosine + beef extract 



(4) 0.1% tyrosine + 1.0% dextrose 

 -f- beef extract 



(5) 0.1% leucine 



(6) 0.1% leucine + 1.0% dextrose 



(7) 0.1% leucine + beef extract 



(8) 0.1% leucine + 1.0% dextrose 



-f- beef extract 



Ph 



4.6 

 4.6 



6.8 



Response 



(9) 0.1% leucine fraction (alanine, 

 leucine, valine) 



(10) 0.1% leucine fraction + 1% 

 dextrose 



(11) 0.1% leucine fraction + beef 

 extract 



(12) 0.1% leucine fraction + 1.0% 

 dextrose + beef extract 



(13) nutrient broth (1.0% peptone 



+ 3 grams beef extract) 



No growth 

 No growth 

 Noticeable clouding 



Fleavy growth 



Noticeable clouding 



Clouding more pronounced than in 



(5) 

 Better growth than in (6) 



Growth as good as in (13) 



Clouding more pronounced than in 

 (5) 



Marked clouding, better than (6) 

 and (9) 



Growth about same as in (7) 

 Growth somewhat superior to (13) 



Good growth 



# The amino acids utilized were kindly supplied by Dr. Barnett Sure. 



It should be explained that the amino acids were dissolved in 

 distilled water, and in the case of tyrosine, hydrochloric acid 

 was added in (1) and (2) to aid in dissolution, the amount of 

 acid added being sufficient, as shown by the P H obtained, to affect 

 growth. The beef extract (Liebig's) was used in the same pro- 



