20 



Harold Thurston Cook 



flower is that the fungus was present in the ovule (figures 5 and 6). 

 A dense mat of mycelium was formed in the hase of this organ (figure 

 6), and also was distributed entirely around the ovule. Since the only 

 material found was immature flowers, it was impossible to determine 

 which tissues of the mature seed would contain the fungus. Neverthe- 

 less the presence of the mycelium in such a large quantity in the base 

 of the ovule suggests that, even though the embryo might not be invaded, 



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* 



Figure 5. longitudinal section showing part of the ovary and one ovule of an 



infected onion flower 



the fungus would remain in the seed coat and the seedling would be- 

 come infected during germination. As a rule, the seed coat of the 

 onion remains attached to the cotyledon. 



Katterfeld (1926), working in Russia, found that the mycelium al- 

 most reached the base of the ovary, but he could find none in the seed. 

 Hiura (1930 a), working in Japan, found that the tissues of the flower 

 stalks, and the perianths, styles, ovaries, filaments, and anthers of the 



