COLEOSPORIUM. 



375 



The aecidia are produced amongst the pycnidia on needles 

 two or three years old ; they have long white peridia and 

 are known as Peridermiuvi dblongisporium Fuck. The. aecidio- 

 spores are yellow when mature, and originate in chains, which 

 in the earlier stages of development consist of intermediate 

 cells and spores, but the former gradually disappear (Fig 208). 

 The spores have an average length of 30-5/« and breadth of 



Fig. 20S. — Po'idi'.vmmni pinl (ColeoR'poruitii senecionis). Portion of an aecidium 

 with basidia (6) giving off spores and intermediate cells (d) ; outside the 

 peridium (p) other basidia (e) with club-shaped ends force up the epidermis ; 

 iL, the thick mycelium in the leaf-parenchyma. (After R. Hartig.) 



20m; iu form they are generally longish-oval, few being round; 

 the spore-coat is moderately thick. Aecidiospores are capable 

 of immediate germination, and produce Uredo-'pa.tches on Senecio 

 by June. 



The uredospores have an average length of 28'5/u, and 

 breadth 15"5/u; they are generally oblong, with a moderately 

 thick coat beset with spiny warts. 



