THE FUNGUS BODY. 



37 



Fig. 34. — Epidermis and a few cortical cells of cowberry with mycelium of Calyptpsfiora 

 occupying the intercellular spaces and pressing knob-like ends a|;ainst the cells from 

 which a slender branch penetrates the wall and enlarges in the mterior into sac-like 

 haustoria, b, b, a, Cy reproductive branches. Magnified 420 diam.— After R. Hartig 



EXERCISE IX. 



Mildew {Microsphara), a surface parasite Examine dried leaf bear- 

 ing mildew. Observe 



1. The whitish interlacing hyph^ on surface of leaf, forming the 

 mycelium. (^ 43.) 



2. The distribution of the fiingus : does it cover the whole leaf or only 

 occur in patches ? Compare the earlier and later gathered leaves as to 

 this. 



3. Demonstration. Scrape a bit of the mycelium from the surface of 

 the leaf after moistening it for a few minutes with a 5^ solution of 

 potassic hydrate. Mount and show [a) the colorless branching hyph^ ; 

 [b] the erect branches bearing the spores ; [c] the spores. 



4. Examine, as before, one of the older leaves. Observe the yellow- 

 ish dots scattered over the mycelium, the immature /rwVj. Associated 

 with these the black mature fruits, which contain sporangia with 

 spores. (^ 271-) 



White rust ( Cystopus portulacce), an internal parasite. 

 I. Demonstration. Boil a leaf of purslane for a minute or two in t,% 

 potassic hydrate. Tease apart the tissues oi leaf with needles on a slide, 



