252 



BOTANICAL GAZETTE 



[OCTOBER 



ends of hyphae already produced; this results in a darker zone sur- 



rounding the lighter zone. 



After maintaining this condition for 



some time, individual threads^ in a scattered fashion, break through 

 the outer dense zone, continue their growth, and proceed to the for- 

 mation of a second lesser zone, followed in course of time by a second 

 denser zone, all being formed in precisely the same fashion that the 

 first two zones were made. Plates have been exposed under different 

 light relations and different temperatures, and it seems probable that 



Fig. II 



Fig. 12 



Fig. II. Pure culture of the fungus 17 days old, gro\vn upon cow pea agar in 



diffuse light; pycnidia not then formed. — Fig. 12. Pycnidia on agar plate, viewed 

 from below. 



there is no connection between either of these factors and formation 

 of zones in this fungus, other than is occasioned by increasing or 

 decreasing growth. 



INOCULATIONS (figS, JJ, 14) 



Some forty inoculations were made with mycelium taken from 

 pure cultures on bits of agar. Of these twenty-eight gave positive 

 results. Control cultures remained uninfected. Inoculations were 

 made within the involucral scales, between the flowers in the head, 



■J 



on stems, and on leaves, as follows: 



Series I 



Inoculated from mycelium obtained from the original agar plate 

 culture on which diseased rays had been placed. Inoculations made 

 November 22, 1906. 



1 



