CHAPTER III 
THE LARCH CANKER (continued) 
The reproductive organs of the fungus. Germination of spores. Puze 
cultures on nutrient media. Artificial infection with canker. 
The reproductive organs of the fungus. The reproductive 
organs are of two kinds: 
1. Apothecia. 
2. Spermogonia or pycnidia, the name depending on the 
interpretation of their morphological nature. 
When fructifications aré about to be formed there first 
appear on the surface of the bark a number of white or pale 
yellow felt-like mycelial outgrowths. These may give rise 
to both apothecia and spermogonia, the latter being generally 
mature just at the time when the former are initiated. 
Apothecia. The youngest stage which I have traced in 
the formation of apothecia consists in a group of hyphae 
standing out from a small portion of one of the mycelial 
masses on the surface of the stem. These hyphae are easily 
distinguished by numerous very fine wart-like outgrowths 
on their walls. The portion bearing them is circular in 
outline, and towards the centre the hyphae are bent inwards. 
Underneath these hyphae there next appears the first 
indication of a layer of hyphae directed at right angles to 
the surface. This layer, which is the young hymenium or 
ascus-bearing layer, becomes broadened by the interpolation 
of fresh hyphae, and the apex of the apothecium opens, 
leaving the warted hyphae as a broad fringe of hairs round 
the hymenium, which is orange in colour. 
The apothecium grows for a long time, reaching a size of 
2-4 mm., orin extreme cases 5mm. The hymenium becomes 
paler with age, and the margin and under-surface are white 
throughout. The whole is raised on a short stalk about 
1 mm. in height and rather less in thickness (fig. 17). 
