CHESTNUT BARK DISEASE. 



43 1 



Connecticut. Of these four, three had been in culture only a 

 few months, while one had been in culture over three years. 



In each test we made three cultures of each of the above 

 for duplication. We grew these on plain potato- juice agar, as 

 checks for comparison, and also on this medium to which had 

 been added the following percentages of tannic acid: 0.2, 0.4, 

 0.8, 1.2, 1.6, 2.4, 3.2, 4.0, 4.8, 6.0, 8.0, 10.0, 10.5, n.o, 11.5, 12.0, 

 14.0 ; see Plate XXVII. These cultures were first made in 1912, 

 and repeated in 1913 for confirmation, this time using five cul- 

 tures of each in each test. The table shows the results of all 

 these cultures in the tubes containing 4% or more of tannic acid. 

 Those containing lower per cents, all grew, and so are omitted 

 in the table. From the results of these investigations we obtained 

 the following information: % 



(i) The growth of either fungus causes no darkening of the 

 plain potato- juice agar, but when tannic acid is added, even as 



