368 CONNECTICUT EXPERIMENT STATION REPORT, IQI2. 



of the summer spores is practically over. It is quite unlike 

 the Cytospora stage in that the spores are borne in sacs, or 

 asci, situated in special receptacles called perithecia. 



The mature perithecia, Plate XXVIII k, are minute, light to 

 dark-colored spherical bodies, situated within, but generally 

 beneath and around, the edge of the pustules. By means of 

 long black necks these perithecia open on the exposed surface 

 of the fruiting pustules, where they show as minute black 

 specks called ostioles. With trie later growth and wearing away 

 of the fruiting pustules these ostioles sometimes project as 

 short spines. Each perithecium contains numerous, hyaline, 

 oblong, asci, Plate XXVIII f, tapering somewhat at their base, 

 within which are eight ascospores arranged one above another 

 in one or two rows. In size the asci usually vary from 40 to 

 45 /x in length by 7 to 9 /x wide, though some vary from 37 to 50 ^ 

 in length. 



The ascospores, Plate XXVIII c, are hyaline, oblong to 

 broadly oval, with a central septum, at which they are often 

 slightly constricted. These spores are usually rounded at the 

 ends, though sometimes somewhat pointed at one or both ends. 

 They vary from 6 to 10 /* in length by 2.75 to 5 /*, in width. 

 While the chief time of germination of the ascospores is 

 undoubtedly in the spring, their production and germination 

 seems to be more or less distributed throughout the year. After 

 rainy weather they are shot through the ostioles of the perithecia 

 with some little force, and no doubt may be carried much 

 further by the wind. By this means their distribution is greatly 

 facilitated, and, because of their greater vigor, some experi- 

 menters believe they are more important in producing infection 

 than the conidial spores. 



Progress of Disease. From our inoculation experiments it is 

 evident that seedling trees one-half inch or less in diameter 

 may be girdled, and in some cases their tops killed in one 

 season, Plate XXV a. Sprouts an inch or more in diameter may 

 likewise be entirely girdled for a distance of six or more inches, 

 so that the death of the parts may be expected at least by the 

 following spring. We have not inoculated the large limbs of 

 trees, neither have we measured the rate of growth of cankers 

 on the same, but we have had under general observation, for 

 several seasons, marked trees at both Stamford and Middlebury. 



