Heald: Discosia on Bull Pine Seedlings 217 



Explanation of Plate XIV. 



Fig. i. One year old seedling of Pinus ponderosa, showing pycnidia on 

 the hypocotyl. Natural size. 



Fig. 2. Pycnidia showing variation in form. 



Fig. 3. Single pycnidium showing the typical elliptical form and central 

 ostiole. 



Fig. 4. Group of spores, showing form, septation, and number of cilia. 



Fig. 5. Single spore, much enlarged, showing insertion of the cilia. 



Fig. 6. Complete cross-section of pycnidium, showing position and arrange- 

 ment of the spores, character of pycnidium wall, and slightly protruding lips 

 of the ostiole. 



Fig. 7. Portion of cross-section of a pycnidium with spores removed to 

 show two of the vertical supporting pillars or columns. 



