236 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



describes a larger boundary. Moreover, since the 

 cambium around the, as yet, undiseased parts has 

 added a further annual ring which of course stops 

 at the boundaries of the diseased patch the 

 centre of the patch is yet more depressed (cf. 



Fig. 34)- 



And so matters go on, year after year, the local 

 injury to the timber increasing, and ultimately 

 seriously affecting, or even bringing to an end, the 

 life of the tree. 



At the margins of the diseased patches, as said, 

 the fungus at length sends out its fructifications. 

 These appear at first as very minute cushions of 

 mycelium, from which the cup-like bodies with 

 an orange-coloured lining arise : the structure of 

 this fructification is best seen from the illustration 

 (Fig. 36, A). The orange-red lining (It) is really 

 composed of innumerable minute tubular sacs, each 

 of which is termed an ascus, and contains eight 

 small spores : as seen in the figure (Fig. 36, B), 

 these asci stand upright like the pile of velvet lining 

 the cup. They are formed in enormous numbers, 

 and go on ripening and scattering the spores, 

 which they do forcibly, day after day. There are 

 many interesting details connected with the develop- 

 ment and structure of these fructifications and 



