72 



MISSOURI BOTANICAL GARDEN 



* 



abundance 



middle 



this stage. Generally this zone appears in the 



young tubercle. The pear-shaped or spherical vesicles, packed 



the 



ds of liyph 



In 



preparing the sections they are often torn loose from the large 



mass 



11). They are quite similar both in shape and content to the 

 vesicles found in the tubercle of the alder, except that in the 

 Ceanothus form there is no double wall such as is pointed 



by 



At first the vesicles 



in 



body (f. 10), which at a later stage increase in size. Subse- 

 quently the material in the vesicle divides into two parts with 

 a very faintly stained substance between them. Apparently 

 this is the mature condition of the fungus and its ultimate 

 products are contained in the sporange-like structure. Al- 

 though not surrounded bv a distinct and perceptible wall 



these parts are quite analogous to spores but the final fate of 

 these structures and their relation to the infection of the plant 



could not be determined. 



At this stage every trace of starch and cytoplasm in the 

 host cell has disappeared, its nucleus becoming very irregular 

 and shriveled, staining a light orange and usually lying near 

 the periphery of the fungal mass (f. 7, 9). However, the 

 nucleole is still quite large, its appearance indicating that it 

 retains its vitality. Thus all the protoplasm of the cell is 

 used by the fungus to build up its structure, and not until 

 there is no more protoplasm in the cell does the degeneration 

 of the fungus begin. This is shown by the gradual contract- 

 ing of the entire fungal mass and the collapse of the walls 

 of the mycelium and vesicles, although occasionally one or 

 two vesicles may be found which are unaffected (f. 13), All 

 signs of nuclei in the fungus disappear and the only thing 

 remaining is the rigid cell wall. At a certain stage in this 

 struggle between, the fungus and its host, one would infer 

 that the fungus is the victor, and it may be temporarily, yet 

 its life, after having attained this stage of development, is 



and its death is brought about by 



