i9o8] EDGERTON—ANTHRACNOSES 373 



When the leaves fall to the ground, the fungus takes on a sapro- 

 phytic mode of life, continuing to develop on the dead leaves, spread- 

 ing much more rapidly on them than it did on the living leaves. It 

 often covers considerable areas, sometimes entirely covering the leaf, 

 and on these areas acervuli and conidia are produced in abundance. 

 Klebahn in developing the perfect stage cut out merely the affected 

 areas, in order to save time in looking over the leaves in the spring. 

 He does not speak of the saprophytic growth of the fungus on the 

 dead leaf, and perhaps, did not observe it; otherwise he would not 

 have taken the trouble to cut out the spots. The conidia develop 

 in these pustules throughout the winter; they were examined often 

 and each time spores were found that were viable, and they were par- 

 ticularly abundant after a fairly warm period of a day or two. The 

 pustules on the dead leaves do not seem to differ from those developed 

 normally on the leaves in the summer. 



During February or March, a different sort of conidial fruit body 

 begins to form in favored positions. In places where the leaves were 

 kept moist, where they were piled up and sheltered from drying, or 

 where they were placed close together between pieces of wire netting, 

 a sort of pycnidium was formed. This is what Klebahn (/. c, p. 548) 

 described as the Sporonema or Fusicoccum stage on dead leaves. The 

 conidia are the same in shape and size as those in the acervuli, but the 

 stroma bearing them has been favored by the moisture and has con- 

 tinued to grow until it has completely surrounded the developing 

 spores. These pycnidia-like bodies {fig. 3) are grayish to black, 

 not imbedded in the host tissue, and generally covered by a rather 

 hairy growth of hyphae; they vary in size, some being over i™"* in 

 diameter. While this structure is a closed one and perhaps would 

 be classed as a pycnidium, it hardly seems to be a true one. It is 

 always more or less irregular and nearly always there are trabeculae 

 consisting of strips or masses of the stroma imbedded with the spores 

 {fig. 3). This shows that the spores and the pycnidial wall must 

 have been developing at the same time; while in a true pycnidium, 

 the wall is formed before the spores begin to develop. 



An examination of the diseased petioles at this time shows the same 

 formation. The pycnidia are developed in the cankered spots so that 

 they appear to be imbedded in the host tissue. In the petioles the 



