Leaf Curl and Plum Pockets. 347 



The tissue of the gall is quite hard, especially so as compared 

 with that of the ordinarj^ "bladders" formed by species of Exoas- 

 cus, and this taken with the scanty mycelium of the fungus and 

 the peculiar shape of the gall is pretty strong evidence that the 

 form of the gall is more strongly influenced by the cecidomid than 

 by the fungus. 



The fungus is very different from those which are known to 

 produce the "bladders" or "pockets" of the irmXs oi Pru7ius. 

 The asci are cylindrical or slightly clavate and rounded at the 

 free ends. Thej^ are 30-40 long by 6-10 in diameter. The stalk 

 cells are very broad, being 6-10 high by 10-15 iii diameter. They 

 are usually rounded and blunt below and do not at all intrude 

 between the cells of the epidermis. The asci are scattered or 

 rather loosely aggregated. Figs. 73, 78, 79, illustrate the asci, 

 etc., of this species. The spores are rounded or elliptical, and 

 very frequently the formation of conidia by budding in the ascus 

 takes place. In a few cases I have observed the spores in process 

 of formation before the wall separating the ascus from the stalk 

 cell was formed. Two such cases are represented in fig. 73. One 

 case was observed where no wall was formed even when the ascus 

 was mature and the spores occupied the entire fruit body. A few 

 variations of this kind have been observed in some of the other 

 species. Sadebeck records a case of the beginning of spore 

 formation before the separating wall was developed. 



Occasionally on the same trees which bear the cecidomid galls 

 with the Exoascus cecidomophilus Atkinson, are the old mummified 

 hypertrophied fruits caused by Exoascus cojifusics Atkinson {E. 

 pruni oi Authors). Fig. 16, Plate VII, shows a very interesting 

 condition of the fruit which is sometimes seen. A single raceme 

 bears several normal fruits, one mummified fruit the result of the 

 attack of E. confusus in May or early June, and several fruits 

 attacked both by a cecidomid and by E. cecidomophilus in July. 



Exoascus sp 



A species of Exoascus has been found deforming the leaves and 

 twigs of Prunus virginiayia, but thus far I have not seen the 

 mature condition though several diligent searches have been made 

 for it. To what species it belongs or whether the one in the 



