439 



lighter brovvn colour. The spots then look as if a brown 

 powder had been strown over them; it might be called a 

 granulated appearance. This description refers particularly 

 to the Libéria cofifee; in Coffea arabica the colour of thc 

 hyphae soon ressembles that of the dead leaf. 



The granulated appearance of the leaves is caused by 

 the formation of knots of hyphae, whieh manifest them- 

 selves as little yellowish brown spots. 



The hyphae are very thick (5 — 7 /<) and run generally 

 quite straight over the leaf surface, they hâve a number 

 of short branch-hyphae, which make wide angles with 

 the main hj^pha; so the microscope shows us a field, 

 divided into almost rectangalar figures (Fig. 5). 



At certain places however accumulations of hyphae 

 arise, when the straight hyphae throw out side branches, 

 which in their turn make side branches of the second 

 order. The small branches of différent hyphae meet each 

 other and become twisted together; so the little nodules 

 are formed, which are visible tothe naked eye (Fig. 5, 6, 7h). 



As mentioned before, one finds the fungus already well 

 developed on leaves, which do not y et show the disco- 

 loured spots. So the question arises how It can be 

 explained that the spots are not seen at the same time. 



Microscopical research showed, that hyphae are never 

 seen in the green parts of a leaf, over the surface of which 

 the membrane is already widely spread"; they are found 

 on the contrary in the brown spots; the hyphae stretch 

 themselves just to the outside of the discoloured parts. 

 A transverse section taken at a place where the silvery 

 tissue was already well developed, but the brown colour 

 was just noticeable, will throw some light over the manner 

 in which the fungus damages the leaves. One may then 

 see, that accumulations of hyphae are formed above the 

 stomata, which lay a little under the leaf surface; then 



