

Fig. 16. — Closeup of an ascospore on a needle immediately prior to germination. 

 The light cell has collapsed and expanded over the surface of the needle. (X 2500) 

 bedded in paraffin. Young, naturally-infected tips were also collected 

 from the field and treated in a similar manner. Longitudinal sec- 

 tions of needles from these tips were prepared and various stages 

 of spore germination and subsequent infection were studied. 



Infection was initiated by mature ascospores as the needles 

 unfolded from the buds. The spores were extremely sticky when 

 moist and became attached to the needle surface (Fig. 15). After 

 contact, the hyaline end of a spore disintegrated and its gelatinous 

 sheath spread outward, thus cementing the dark end firmly to the 

 needle. A small protuberance from the black cell (Fig. 16) was the 

 first indication of germination, unless germination had occurred 

 previously in the fungus apothecium as described. The young, dark- 

 colored germ tube elongated and soon after penetration of the epi- 

 dermis became hyaline and septate. Penetration was directly through 

 the cuticle as observed by Van Vloten (63). Hubert (23) suggested 

 that the fungus mighi penetrate the needles through stomatal open- 

 ings, but entrance through stomata was not observed in this study. 

 An infection peg passed through the onto wall of an epidermal cell 



39 



