240 ANNALS OF THE MISSOURI BOTANICAL GARDEN 



fVOL. 10 



Dextrose 100 per cent 



Citric acid 99.8 per cent 



Oxalic acid 98 . 1 per cent 



Malic acid 97 .5 per cent 



Tartaric acid 99 . 3 per cent 



The above figures are only indicative of the general efficiency 

 of the method, since it is very difficult to obtain some of the 

 above acids in a pure state or to prepare accurately known solu- 

 tions by ordinary methods. Some of the readily volatile sub- 

 stances, such as acetic acid and the lighter alcohols, are not 

 oxidized by this method, and whether this is due to their volatili- 

 zation or to their natural resistance to such an oxidation is 

 undecided. Succinic acid is likewise unoxidized, possibly due 

 to the formation of the stable succinic anhydride. It will be 

 found, however, that the common fruit acids and sugars yield 

 results of a good grade of accuracy by this method. 



Experimental Work 



THE FUNGI EMPLOYED 



In carrying out the physiological work reported here a con- 

 siderable number of fungi was used. Some of the cultures proved 

 to be poorly adapted to culture work or too irregular in growth 

 on artificial media and had to be abandoned, e. g., Pythiacystis 

 citrophthora which failed to grow consistently in any liquid 

 medium, and Oospora Citri-aurantii which was found very 

 interesting but impracticable to use, due to the fact that no 

 mat is formed, the growth breaking up to form a fine sediment. 

 Some of the cultures were not obtained until the work was 

 well under way and others failed to respond satisfactorily at 

 various times; thus, in numerous phases of the work complete 

 data on some of the fungi are lacking. A satisfactory culture 

 of Penicillium italicum was never obtained, the culture used early 

 in the work being so attenuated that it refused to infect oranges, 

 and another used for a time as P. italicum proving later to be a 

 different species (so identified by Dr. Thorn). Nor was P. itali- 

 cum found on rotting fruit in the St. Louis market during the 

 winter. This was a disappointment since this fungus is un- 



