1919] KEMPTON—PYCNIDIUM 257 



46. VON Tavel, Franz, Beitrage zur Entwickelungsgeschichte der Pyre- 

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47. , Vergleichende Morphologic der Pilze. Jena. 1892. 



48. Webber, Herbert J., Sooty mold of the orange and its treatment. 

 U.S. Dept. Agric. Div. Veg. Phys. and Path. Bull. 13. 1897. 



49. Wenner, John T., A contribution to the morphology and life history of 

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50. Wolf, Fredrick A., The perfect stage of Actinonema rosae. Box. Gaz. 

 54:218. 1912. 



51. , Some fungous diseases of the prickly pear, Opuntia Lindheimeri 



Engelm. Ann. Mycologici. 10:113. 1912. 



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Deutsch. Akad. 40:1878. 



EXPLANATION OF PLATES XVII-XXII 



The drawings were made with a Leitz camera lucida and a Leitz one- 

 twelfth oil immersion lens or a no. 6 objective. The scale appears on the 

 plates. 



PLATE XVII 



Phoma 



Fig. I. — P. herharum West: 4-celled stage of pycnidial primordium of 

 simple meristogenous origin. 



Fig. 2. — Slightly later stage. 



Fig. 3. — Stage similar to fig. 2. 



Fig. 4. — Young pycnidium with light colored rostrum where ostiole will 

 form. 



Fig. 5. — Mature pycnidium and spores formed by simple meristogenous 

 development. 



Fig. 6. — P. pirina (Fries) Cooke: few-celled stage; simple meristogenous 

 origin. 



Fig. 7. — Shghtly later stage. 



Fig. 8. — Many-celled pseudoparenchymatous stage with branches protrud- 

 ing from mass. 



Fig. 9. — Irregular mass from which pycnidium develops. 



Figs. 10, n. — Few-celled stages in origin of which 2 or more hyphae are 

 involved; compound meristogenous origin. 



Fig. 12. — Similar to fig. 11, but slightly older. 



Fig. 13. — Primordium in which a 3-parted hyphal strand is involved. 



Figs. 14-16. — P. destructiva Plowr.: beginning stages in pycnidial develop- 

 ment; simple meristogenous origin. 



Fig. 17. — SUghtly later stage. 



Figs. 18, 19. — Compound meristogenous development in which 2 or more 

 hyphae are involved. 



