HELIOTROPISM OF ASCI IN DISCOMYCETES 311 



Fig. 152. — Morchella esculeitld. A fruit-l)ody (receptacle) with its stipe and pileus. 

 The pileus is hollowed out externally into pits (alveoli) each of which is lined 

 by a hynieniinn. The various hynienia are separated from one another by ribs 

 which are sterile aloufj their outer edges. The asci of each hynienial pit are helio- 

 tropically curved toward the pit's mouth and, therefore, tliey shoot their spores 

 away from the fruit-body. Thotographed in Yorkshire, England, by A. E. 

 Peck. Natural size. 



