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THE BOTANICAL MAGAZINE. 



[Vol. XXX. No. 357. 



fungus. From autumn to winter, the ascosporous stage develops 

 gradually- as'thc larger pustules ; and it is sometimes observed 

 that the long necks of the perithecia arc pushed out from these 

 stromata as black threads. 



Fig- 



In the case of a larger tree, the disease appears first mostlj^ 

 from the tip of its branches and works gradually downward 

 tow^ard the larger limbs and trunk. The disease progresses with 

 a great rapidity' in the direction of the long axis of the stem, 

 and in many cases the affected portion reaches from the tip of 

 the stem to its base in the course of one or two years, as a 

 sunken canal or canals on the side of the trunk. The disease 

 works, however, rather slowdy requiring a longer time to com- 

 pletely girdle the larger trunk. The affected area of the trunk 

 soon becomes sunken, making the boundary- between the dead 

 and living tissues very marked. Callus formation soon takes 

 place from the edge of such an affected area, and in consequence 

 often the bark at the boundar}- lines is more or less cracked, 

 presenting somewhat a cankered appearance (Fig. 3). The bark 



