206 ASCOMYCETES. 



asci, the latter with eight or fewer bicellular dark-coloured 

 spores. The mycelium is dark-coloured, very vigorous, and 

 furnished with many lateral bladder-like outgrowths ; it permeates 

 the whole cortical tissue as far in as the wood, and under the 

 epidermis forms a brown pseudoparenchymatous stroma, which 

 extends over the cortex, and gives rise to numerous perithecia. 

 The living cells of the cortex turn brown in presence of the 

 fungus-mycelium, and collapse, causing the whole shoot above 

 the place of attack to wither and die. 



Cucurbitaria. 



The dark perithecia and pycnidia break through the epidermis 

 in large numbers. The asci contain six to eight brown spores, 

 divided by cross-septa. 



Cucurbitaria laburni Pers.^ (Britain). The spores of this 

 fungus germinate on wounded parts of laburnum (Cytisus 

 Lahurnum), and, as the branches of attacked plants soon die 

 off, considerable damage to nursery stock may result. The 

 mycelium spreads through the wood, particularly the vessels, 

 in spite of the early stoppage of these by a yellow wood-gum. 

 Diseased parts of the wood of living branches appear as dark 

 strips ; reproductive organs are produced in the bark, and 

 there the plant attempts to isolate the diseased parts by con- 

 tinued cork formation. 



If diseased, but still living spots on stems be examined, 

 they will be found to include many yellow and black pustule- 

 like swellings, some buried in the bark under a periderm eight 

 to ten cells in thickness, others in process of breaking through 

 or altogether exposed. Many of the pustules will attract 

 attention from the presence of red, twisted, elongated tendrils 

 on them. On the lower parts of dead branches the same 

 appearances will be found, but, in addition, the periderm will 

 generally be ruptured, and the openings so produced filled with 

 spherical dark grey or black fructifications. These are variable 

 in form, and amongst them can be distinguished some which 

 are very large, round, smooth-coated, and light-coloured, with 

 a round pore ; others, which appear more warty, and have a 

 depressed opening ; while still others, generally smaller, have 



^ V. Tubeuf, ''Cucurbitaria laburni." Botan. Centra/blaff, xxvi. , 1880. 



