346 Bulletin 73. 



• 



fungus. Certainly the larvae control to the greater extent the 

 form of the gall, which is very different from that produced by any 

 hitherto known species of the Exoasceae . Neither the floral en- 

 velopes nor the stamens suffer hypertrophy, the carpel alone being 

 concerned. This is transformed into a peculiar hollow and open 

 gall, the opening being at the base of the ovarj^ and appearing as 

 if it were formed by the cracking away of a portion of the base 

 from the receptacle, as the base of the fruit by hypertrophy in- 

 creases in size. The peculiar shape of the gall is shown in figs. 

 15 and 16, Plate VII, reproduced from a photograph. They are 

 from 1.5-2.5 cm. long and somewhat less than i cm. in diameter, 

 being two to three times longer than broad. The}^ are somewhat 

 broader than the normal fruit and two to four times longer, as can 

 be seen in the illustration in which are shown a few normal fruits 

 attached to the same cluster. Sometimes only one or two of the 

 fruits in a raceme are affected. This trouble seems to be a very 

 common one in the vicinit}' of Ithaca, N. Y. It is especially abun- 

 dant along the Dry den road between Aetna and Varna, where it was 

 first noted by Prof. J. H. Comstock. The gall is nearly oblong 

 in outline, with rounded ends, a slight inflation at the middle 

 and a constriction near the base, so that the very base seems to 

 flame outward as if inverting. It is also more or less curved. 



The fungus does not occupy the entire gall and does not pene- 

 trate to a very great depth in the tissues, while the mycelium is 

 rather scanty. Sections, however, do show that the mycelium 

 penetrates in the subepidermal tissue to some extent between the 

 cells over a portion of the gall. The side of the gall which is 

 affected by the fungus is more strongly arched than the unaffected 

 side. Whether the slight curve which has thus far been observed 

 to be present to some extent in all the galls examined, is caused 

 by the presence of the mycelium, has not yet been determined. 

 Several have been examined and the mycelium not found, but 

 farther study is necessary to determine this point, and also to 

 determine the exact relation of the cecedomid to it. 



Before the galls die if they are cut open, several of the reddish 

 larvae of the cecidomid will be found inside clustered at the apex 

 of the hollow interior. The cavity is quite large and smooth, 

 and of a dark color. 



