FUNGOUS ROOT-TUBERCLES. 97 



Elaeagnus. 



The 



tubercles are not found as abundantly as on Ceanothus. 

 Regarding the form and structure, several resemblances can be noted. 

 12. External and internal infection takes place as in Ceanothus. 13. 

 The fungal mycelium differs from that of Ceanothus in being very 

 narrow. It branches profusely, forms the vesicles, the content of 

 which breaks up into several segments. The infected cell passes 

 through various stages. The fungus is not entirely absorbed by the 

 digestive cell. 14. The walls of the host cell are not broken down as 

 a result of the fungal infection. 15. Hypertrophied cells and nuclei 

 are formed, but the nucleo-cytoplasmic relationship is maintained in 

 the infected cells. 16. No ' ' Exkretkorperchen, ' ' such as Zach reports, 

 can be found in the digested cells. 17. Both the host cells and the 

 fungus die as a result of their previous relationship. 



Myrica. 



18. The tubercles and fungus of Myrica differ in many respects from 

 those of Ceanothus and Elaeagnus. All species of Myrica possess 

 tubercles. 19. The fungus confines itself to one or two layers of 

 cells and internal infection takes place acropetally. No hypertrophy 

 or symbiotic relationship exists. 

 parasite. 



as 



fungu 



which change to club-shaped structures in which no further differenti- 



ation takes place. 



fungu 



to that in Ceanothus. 22. The form, structure and behavior of the 

 fungus indicate that it belongs to the genus Actinomyces. 



Enzymes. 



23 



ent capable of digesting fibrin. Whether two enzymes are present, 

 one produced by the host and another by the fungus, could not be 

 determined without a pure culture of the fungus. 



INDEX OF LITERATURE. 



1. Atkinson, G. F. '92. The genus Frankia in the United States, 



(Bull. Torrey Bot. Club. 19:171-177). 



2. Bjorenheim, C. G. '04. Beitrage zur Kenntnis des Pilzes in den 



Wurzelanschwellungen von Alnus incana. (Zeitschrift fur 

 Pflanzenkrankheiten. 14 : 128-134) . 



3. Bourquelot, M. E. et H. Herissey. '95. Les ferments solubles 



de Polyporus sulphureus. (Bull. Soc. Myc. de France. 



11:235-240). 



4. Brefeld, C. '02. Versuche iiber die Stickstoffaufnahme bei den 



Pflanzen. (Centrb. fur Bakt. u. Parasitenkunde. 28:24-25). 



