1916] 



PARASITIC RHIZOCTONIAS IN AMERICA 



371 



the distance on the inner side from the parent hypha to the first sep- 

 tum of the branch, were measured. Ten cells df each strain were 

 measured, and the averages of these measurements used for compari- 

 son. 



As shown in Table 12, the measurements varied considerably, and 

 this was true even with strains from the same host. In the three car- 

 nation strains measured, the length of the mycelial cells varied from 

 70/x to 181.7^', a difference of 111.7^. However, the average of ten 

 measurements brings the difference down to some extent. A still more 

 striking difference was noted in the strains from Dianthus, where 

 the smallest reading was 50/x and the largest 215/x, a difference of 165/x. 

 Similar differences were also found in comparing the two other meas- 

 urements. 



In all cases, altho the table does not bring out this point, different 

 measurements of the cells of the various strains overlapped. For ex- 



TABLE 12. MEASUREMENTS OF MYCELIAL CELLS OF EHIZOCTONIA 



