PERISPORIALES 



203 



do not loosen even toward spring; if in the course of the winter, the peri- 

 thecia dry, they shrink evenly so that the spherical form is not altered. 

 The perithecia remain clinging to the substrate and only later, together 

 with the mycelium, are washed away. Thus the appendages here serve 

 for gripping the mycelium and indirectly, the substrate. 



Fig. 128. — Types of appendages. Microsphaera Alni. 1. On Syringa. 2. On Cornus 

 alternifolia. 3. Var. Lonicerae. 4. Podosphaera Oxyacanthae. 5. Uncinula Aceris. 6, 7. 

 Uncinula Sengokui. (X 270; after Salmon, 1900.) 



Fig. 129. — Phyllactinia corylea. 1. Perithecium with penicillate cells above, a turgid 

 spherical cell on the right, a collapsed spherical cell on the left. 2. Erect perithecium 

 with an apical drop of gel. (1 X 200; 2 X 100; after Neger, 1901.) 



In the second group, with dorsiventral rind, the perithecia are mobile ; 

 they gradually break loose from the substrate, fall off more or less spon- 

 taneously and are carried away by external agents. This active loosen- 

 ing from the substrate is caused either by the action of the rind or of 

 the appendages. 



The cooperation of the rind in the liberation of the perithecia is 

 credible for Uncinula and Microsphaera. Upon drying, the whole rind 

 does not shrink evenly, but only its thin- walled, lower surface; this 

 becomes more or less concave inwards and thereby (especially with 



