SPHAERELLA. 



213 



spring in the fallen needles, which lie on the ground over 



winter. The ascospores are mature and capable of infection 



at, the beginning of June. In forests of 



pure larch, or in mixture with spruce, the 



ascospores are easily distributed by wind. 



In larch, underplanted with beech, the spores 



are kept down towards the ground by the 



canopy of beech foliage, so that, during the 



summer, they cannot be carried up to the 



larch crown. 



Hartig gives the following interesting facts 

 on its distribution. „ ^ , 



, , , . - . , FlQ. 103.— a, Rod-3baped 



" As already remarked, the perithecia de- conidia before and after 



■ ii /■ 11 11. Jl detachment from the 



velop in sprms on the fallen larch needles, basidia. b, Mioro-comdia 



■^. J^ ° from the interior of the 



and in low-lying localities the spores reach cushions, x 4}°. (After 

 maturity at the beginning of June. New »■ Hartig.) 

 conidial cushions are not found on the larch in our neighbourhood 

 before July. The parasite has thus four months at its disposal- 



Fio. 104. —Sphaerella laricina. Section through a diseased larch needle in June 

 after it has lain on the ground from the previous year. The mycelium is thick, 

 thick-walled, and of a light-brown colour. The perithecia contain asci and asco- 

 spores. To the extreme right is a pycnidium containing little oblong conidia, 

 alongside a perithecium. x ^-^. (After R. Hartig.) 



for distribution by means of conidia. As, however, we ascend 

 into the mountains, the snow lies longer, so that the perithecia 

 cannot begin to form so early, the ascospores are correspondingly 

 late in reaching maturity, and the season during which the 

 parasite may spread is still further shortened by the earlier 

 commencement of winter. At an elevation of 1500 metres. 



