Fig. 



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Fig. 



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Fig. 



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Fig. 



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[LLUSTR AT I ON S 



Fig. 1. — Douglas-fir infected three years by Rhabdocline 



pseudotsugae 18 



Fig. 2. — Cross-section of a stem of Douglas-fir infected 



five years 19 



Fig. 3. — Lower surface of Douglas-fir needles covered with 



mature apothecia of the fungus 23 



Moth-eaten appearance of twigs when the needles 

 have been infected 26 



Cross-section through an apothecium 27 



Expulsion of the ascospores from asci 29 



Cross-section of asci and paraphyses 30 



Partially mature ascospores recently released from 

 the asci 31 



Fig. 9. — Typical early germination stage of the ascospores. 32 



Fig. 10. — Typical lateral germ tube shortly after its emergence. 33 



Fig. 11. — A germinating ascospore within the apothecium 34 



Fig. 12. — Abnormal enlargement of the hyaline cell of an 



ascospore 35 



Fig. 13. — Ascospore discharge at the Camden plantation, 1956. 36 



Fig. 14. — Ascospore discharge at the Cortland plantation ,1956. 37 



Fig. 15. — Ascospores adhering to the surface of a young needle. 38 



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



germination 39 



Fig. 17. — Globular oily hyphae of R. pseudotsugae in the 



mesophyll cells 47 



Fig. 18. — Concentration of hyphae against the endodermal 



wall 48 



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