MYCOSPHAERELLACEAE 215 



by Ellis in 1880 as Sphaeria bidwellii, and about a dozen other 

 binomials have subsequently been applied to it. The most ex- 

 tensive studies of this fungus are those of Reddick (1911). Its 

 pvcnidial stage belongs to Phvllostictina and is characterized by 

 large spherical to ellipsoidal hyaline but granular pvcnidiospores. 

 These appear in lesions on leaves, canes, and berries. Reddick 

 noted microconidia, produced in pycnosclerotia, which occurred 

 among the true pycnidia, especially on shrivelled berries. These 

 undoubtedly are spermogonia, and archicarpic sclerotia should be 

 looked for, interspersed among the pycnosclerotia. In the spring, 

 in the leaves and berries that have overwintered on the ground, 

 are mature perithecia. They contain hyaline, unequally two- 

 celled ascospores that become septate at time of maturing. 



Giiignardia baccae, possessing larger ascospores than those of 

 G. bidnxeUii, is regarded as the cause of grape black rot in the 

 Caucasus region. Undoubtedly still other species are responsible 

 for diseases of muscadine grapes native to the southeastern United 

 States. 



Ventiiria. Several species of \^enturia are concerned with scab 

 diseases of pomaceous fruits. Of these V, inaeqiialis of apples, 

 involving leaves, flowers, fruits, and twigs, is the most widely 

 known. Its conidial stage, Fiisicladiinn dendriticiim, forms stro- 

 matic cushions beneath the cuticle, and from their surface conidia 

 are abstricted. The pathogen may hibernate in the conidial stage 

 on twigs, but more commonly its survival is accomplished by 

 the perithecial stage, which develops throughout the winter and 

 matures in the spring in decaying leaves. 



The initiation of perithecia was described by Killian (1917) 

 and has been confirmed in essential features by several investiga- 

 tors. A coiled hypha arises within a fungus stroma. The cells 

 at the periphery of this stroma are uninucleate, and their walls 

 become thickened, v/hereas the inner cells remain thin-walled and 

 multinucleate. One of these thin-walled cells produces a chain 

 of cells, the ascogonium, each cell of which is bi- to quadrinu- 

 cleate. The apical cell becomes clavate and is the trichogyne. 

 Meanwhile, near the developing ascogonium another hyphal tip 

 thickens and becomes lobate, and paired nuclei migrate into its 

 lobes. This structure is the antheridium. Its growth continues 

 until the lobes contact the trichogyne and become closely appHed 

 to it. A pore then forms, and the antheridial content empties 



