GR.\SSE3 OF IOWA. 



223 



Fig. 109. lOorn smut {Ustilago maydis) germination of spores in water. 



4. "The infection is j)robably through the conidia and not 

 directly from the spores. Bref eld's investigations, mentioned 

 elsewhere, seem -to demonstrate this. 



5. "The period of incubation, or time between iafection and 

 the appearing of smut boils, is about ten days. 



6. "It is probable that the early infections come from the 

 spores of last year, which germinate on the ground at the first 

 favorable weather in the spring, while the later and more 

 abundant infections are from the new spores developed early 

 in the season. ' ' 



Professor Morini* seems to have established the fact that the 

 passage of spores through the intestinal tract favors the ger- 

 mination and penetration of the sporidia in its host plant. 



*Morini. II. Oarbone dalle piante Chimica Veterinaria 7: See Loverdo Les Mala- 

 dies Crypt. 76. 



