Cjbyptogamio Botany and Pla.nt Pathology. 417 



Under normal conditions the fungus is confined to well defined 

 spots on th.e leaf "\Aitli an irregular, slightly raised border. Dur- 

 ing excessiveh' wet weather, as the leaf tissue is dying, it may 

 spread to portions of the leaf where the spots are not so well 

 defined. Such conditiouis also induce a much longer gi'owth of the 

 tufts of hyphae and their conidia. Fig. 5 a and d represent such 

 fonns in comparison ^ith b and e developed under normal con- 

 ditions. The measurements, including such variations, are as 

 follows : Hyphae, 50 — 150x4 — 5 ; conidia, 50 — 280x4 — 5. The 

 figures are aU di'awn to the same scale, using compensation ocular 

 No. fi and objective 4mm, Zeiss, with aid of camera lucida. The 

 micrometer scale of this combination is also projected by the side 

 of the figure. 



GEO. F. ATKINSON. 



All the figures where the scale is shown are drawn with the same combina- 

 tion, the object being magnified thirty times more than the scale. 



53 



