21; 



ASCOMYCETES. 



abjoiiited (Fig. 103); in the interior of the spots are produced 

 tiny conidia {Lcptostroma laricinum), incapable of germination. 



Fig. 101.— Tuft of larch needles, the greater number of which are more or less 

 attacked by Sphaerella laricina. (After R. Hartig.) 



The rod-shaped conidia infect particularly the lower needles of 

 the crown, and three weeks thereafter new conidial cushions 



M^ 



T^ff^ 





Fifi. lO^i.— Sphaerella laricina. Section through a diseased spot on a larch 

 needle. The interior of the leaf is permeated with the intercellular mycelitim. 

 Two conidial cushions are shown ; from these numerous long rod-shaped conidia 

 are given off externally (those of the upper cushion have nearly all been carried 

 off by rain), while cavities inside the cushions are filled with micro-conidia. 

 X if ii. (After R. Hartig.) 



appear. Their distribution and germination are facilitated by 

 wet weather. The perithecia (Fig. 104) are matured towards 



