234 BOTANICAL GAZETTE [October 



" meristogenous " when the primordium arises from a single 

 hyphal cell or a group of adjacent cells of a single hypha by con- 

 tinued cross and longitudinal division. In the latter, branches from 

 neighboring cells or from the mass itself may share. A number of 

 variations of these 2 methods have been described. Classification 

 of the pycnidial developments described by Bauke according to the 

 methods distinguished by DeBary places Cucurhitaria as meris- 

 togenous ^Diplodia as symphogenous, and Pleospora polytricha as a 

 combination of the two. 



ZoPF (52) in 1890 mentioned 3 types of pycnidial development : 

 ''Hyphenfrucht," "Gewebefrucht," and "Knauelfrucht." The 

 "Hyphenfrucht" comprises those in which development proceeds 

 from a single hyphal cell which by dividing and swelling forms a 

 quadrant, from which with the aid of 2 or 3 neighboring cells a 

 primordium is formed. By " Gewebefrucht " is designated those 

 instances in which a tissue mass is formed. This mass may develop 

 in either of 2 ways: by neighboring cells of a hypha becoming 

 septate, swelling, dividing, becoming more rounded, while short 

 dividing hyphae either from the mass or from neighboring cells 

 of the hypha share in the formation ; or in a like manner it may be 

 formed from cells of 2 or more contiguous hyphae. The "Knauel- 

 frucht" develops a primordium from i or more short h3^hal 

 branches which coil spirally, branch, and interweave into a knot 

 which later develops into the pycnidium. The " Hyphenfrucht " 

 and " Gewebefrucht " are clearly variations of the meristogenous 

 method of development of DeBary. The other, "Knauelfrucht," 

 is symphogenous. 



In addition to these should be mentioned the " sporopycnidivun " 

 of VON Tavel (46) , referred to also by Planchon (29) and Schnegg 

 (33). This pycnidium arises meristogenously, according to voN 

 Tavel, representing the most extreme case of meristogenous 

 development. A single spore in the presence of abundant food 

 germinates and grows a short mycelium; then by division and 

 growth becomes a pycnidium. Reddick (31) notes that pycno- 

 sclerotia may be found in Guignardia. These bodies arise as 

 pycnidia, produce pycnidiospores, and later function as perithecia, 

 producing asci and ascospores. 



