164 



BOTANY. 



velvety appearance, which is due to the fact that its sur- 

 face is covered with myriads of short, jointed, vertical fila- 

 ments, each of which bears one or more conidia (Fig. 89, 1). 

 The conidia, which fall off readily, are produced until the 

 latter part of summer, when the filaments which bear them 

 shrivel up and disappear. 



342. During the latter part of summer spore-sacs are 

 produced, but require the greater part of winter to come 

 to perfection. The spore-sacs grow in the cavities of mi- 



Fia. 89.— Structure of Black Knot. 1, filaments bearing conidia; 2, stylo- 

 spores; 3,_ahollow papilla Cperithecium) containing spore-sacs; 4, spore-sacs and 

 spores, with tliree slender filaments (paraphyses); 5, a spore; 6, spores germi- 

 nating. AU much magnified. 



nnte papillae (perithecia), and are intermingled with slender 

 filaments (paraphyses, 3 and 4, Fig. 89). Each spore-sac 

 contains eight spores, which eventually escape through a 

 pore in the top of the sac. These spores germinate by 

 sending out a small filament, or sometimes two (Fig. 89, 6). 



343. Besides the perithecia, there are other cavities 

 found which much resemble them and contain other sup- 

 posed reproductive bodies. 



344. No sexual organs have as yet been observed. 



