THE LARCH CANKER 39 



and the short axis 9-10 ju. Each contains, when ripe, a single 

 central nucleus and a large hyaline vacuole, containing 

 glycogen, on each side of it, lying with it in the long axis 

 of the spore. The wall is thin, but appears with a double 

 contour under a D objective. The spores are ejected by 

 a sudden squirt action to a height of about half an inch, 

 and after ejection the top portion of the ascus can be seen 

 to be bent back as in fig. 19. 



The apex of the ascus, at any rate in my specimens, does 

 not turn blue with iodine. As some authors have described 

 this as a feature of the fungus, it is apparently variable in 

 the species. 



The paraphyses (fig. 18, p) are thin hyphae which ^ are 

 found between the asci. They are unseptate and very fine, 

 1-5-2/x in diameter, and about 30 /^ longer than the asci. 

 The apices are scarcely perceptibly swollen, but they tend 

 to bend over the asci and protect them. When kept in 

 a saturated chamber the whole apothecium often becomes 

 filled with a drop of water. This is probably secreted by 

 the paraphyses, and as the secretion presumably continues 

 in a dry atmosphere also, it may serve by evaporation to 

 moisten the air round the asci and save them from drying up. 



Fresh asci continue to be formed for a long time. They 

 appear as short swollen hyphae growing up from the sub- 

 hymenial layer, but ascospores cannot be traced in them 

 until they are fully grown. 



The margin of the apothecium is covered by stiff bristle- 

 like hyphae, which, as described on p. 35, have numerous 

 very fine warts on their walls. Anderson (1902) describes 

 these warts as crystals of calcium oxalate. But I find that 

 they do not dissolve in acetic ax?id or in dilute sulphuric 

 or nitric acid. I am inclined to regard them, therefore, as 

 outgrowths of the wall substance. 



The same general description applies to the apothecia 

 found on dead branches. These are, however, smaller, and 

 for their dimensions the reader is referred to p. 79. 



Spermogonia (fig. 18, B, c). The spermogonia are a-lso 

 formed on the mycelial cushions, and may be found on the 



