CORN SMUTS AND THEIR PROPAGATION 149 



3. Brefeld showed that the spores of some species of smut 

 will not germinate at all in water, but that all kinds germinate 

 in an organic food solution and generally produce conidia or 

 secondary spores, sometimes very abundantly. Thus the 

 smut fungus growing parasitically in its host tissue produces 

 one kind of spore — the chlamydospore ; and this spore growing 

 saprophytically in an organic food solution produces another 

 kind — a secondary spore, the conidium, or sporidium of older 

 writers. I propose, in order to indicate the existence of these 

 two sources of food supply, to call the smut fungus " heterositic " 

 (Greek heteros, one of two, the other; and sitos, food). The 

 ordinary rust fungus is hetercecious, needing two different 

 hosts, to complete its life-cycle. 



4. The infection of the host in the case of oat plants takes 

 place in the seedling stage — the fungus incubates or leads a 

 concealed life in the host and only shows its presence by its 

 dark-coloured spores in the oat inflorescence. 



5. In the case of wheat and barley the seedling is not 

 attacked by the smut spores. Here it is the flowers which 

 give entrance to the pest, which reveals itself first in the crop 

 in the following season. Hecke has infected barley flowers 

 by moistening them with water containing smut spores in 

 suspension. 



6. In Indian corn the seedlings are immune, but localised 

 smut tubercles occur, owing to local attack, wherever young 

 tissue is exposed to the invasion of the aerial conidia of the 

 smut of this host. 



7. Fungicides and rotation of crops are effective means of 

 protecting oats. 



8. Fungicides are useless for wheat and barley grain treat- 

 ment, because the seedlings are immune to external attack 

 and the internal mycelium is not reached by the fungicide. 

 Safety lies only in securing seed from healthy crops. 



9. Fungicides are useful for Indian corn, because by them 

 any adhering spores are killed and the aerial conidia are thus 

 prevented from forming. 



