278 COMPARATIVE MORPHOLOGY OF FUNGI 



The first advance from these forms is the production of a rich 

 mycelium about the fructifications, within the substratum. This soon 

 results in the development of a differentiated entostromatic area bounded 

 by a blackened marginal zone. From this stage we may discern four 

 developmental series. 



The first series includes the species of Diatrype with an effused or 

 isolated stroma. It is characterized by the formation of a strongly 

 developed, deciduous ectostroma, which throws off the periderm from 

 the entire surface of the equally well-developed entostroma, whose 

 darkened surface layers then form the widely erumpent disc. This 

 development of entostroma gives a distinct and abrupt margin to the 

 erumpent stroma. The perithecia are arranged parallel to one another 

 in a single layer; they have short stout necks and are separately erumpent 

 through the encrusted surface of the entostroma as sulcate, disciform 

 ostioles. The conidia are always formed from ectostromatic tissue, 

 and are long filiform, unicellular, curved and hyaline. 



In Diatrype stigma, the perithecia are imbedded in a strongly dif- 

 ferentiated entostroma, bounded by a blackened marginal zone. On 

 the surface of the bark there is early developed an effused layer of ecto- 

 stroma which swells rapidly at maturity and throws off the periderm 

 over large areas. This exposes the developing entostroma whose surface 

 is then rapidly blackened, forming an erumpent disc. The young ecto- 

 stroma increases greatly in thickness at various points and in these cush- 

 ions of tissue, labyrinthiform conidial locules are formed (Fuisting, 1867; 

 Wehmeyer, 1926). 



In D. tremellophora (Wehmeyer, 1926) and D. disciformis (Ruhland, 

 1900) the ectostroma is thrown off by the developing entostroma. 



Diatrype disciformis is at first parasitic, then saprophytic on stems and 

 twigs of beech, rarely on other frondose woods. Between the bark 

 parenchyma and the periderm, the hyphae intertwine into a flat disc 

 which gradually curves in the middle into a blunt head, the later ecto- 

 stroma (epistroma of Fuisting, 1867) (Fig. 184, 1). On account of its 

 harder consistency and rapid growth it exerts such a pressure on the 

 periderm that it raises it in the form of flat pustules from the bark 

 parenchyma. Around the base of the head, there develops a flat cavity 

 into which the conidiophores grow from the disc parenchyma and cut 

 off an enormous number of small much-twisted hyaline conidia, which are 

 flesh red in mass (Fig. 184, 2). 



The cap itself remains sterile. By its elongation the periderm is 

 ruptured and the conidia are liberated through the tear. Gradually the 

 abscission ceases and the hyphae are retained as the ground tissue of 

 paraplectenchyma. The hyphae of the cap, which by the rupture of the 

 periderm are exposed to the air, begin to swell, turn brown and gradually 



