169 



3. Morphological characters are largely altered by environment. 

 Quantity' as well as quality of food produces change in characters. Humid- 

 ity has an important influence on the production of conidia, on the 

 aerial mycelium, and on sclerotial formation (p. 93), influencing even 

 conidia length (p. 95). 



4. The optimum temperature for growth is about 25 (p. 98). 



5. Carbohydrates in the medium favor production of a dark color 

 (p. 100). 



6. Marked effect of nutrition conditions on conidial length, septation, 

 and shape was noted. 



7. From the above findings it follows that collections to be compar- 

 able must be made under similar conditions as regards the factors men- 

 tioned (p. 102). 



8. A procedure to secure standard conditions for study of the fungus 

 was devised (p. 180). 



9. The mycelium, aerial and submerged, is described. The cells 

 bear several nuclei. The senescent mycelium undergoes autodigestion 

 (p. 108). 



10. Conidia show distinct basal and apical markings. The wall is in 

 two layers: the outer (episporium), thin and brittle; the inner (endospo- 

 rium), thick and gelatinous (p. 111). 



11. Germination is usually terminal; anastomosis of germ-tubes is 

 common (p. 115). 



12. The conidia are thickest at a point between the base of the conid- 

 ium and its middle point. The concepts ' 'coefficient of longitudinal ec- 

 centricity" and "coefficient of cylindricity" are introduced for purposes 

 of more accurate description (pp. 117-120). 



13. Conidial length, breadth, and septation are studied biometrically. 



14. For comparison, a biometric study was made of H. ravenelii 

 (p. 121). 



15. The etiological relation of the Helminthosporium (H. No. 1) to 

 foot-rot was demonstrated by its constant presence, by the absence of other 

 parasites, and by its proved ability to cause infection and rotting under 

 various conditions, as by inoculation of seedlings in Petri dishes, in rag 

 doll, and in soil (pp. 124-128). The fungus was shown to enter cells of leaf- 

 sheath, stem, and root. 



16. A study of the infection phenomena shows important changes in 

 the cell-walls of the host; and the development of appresoria and a callus- 

 like formation (p. 128). 



