InfecUnn. 



33 



Hecke^, in 1905, also deinonstrated that the myceUum of the fungus was 

 in the embryo of the barley, even while still enclosed in the seed, after the 

 infection of the flower with the spores of naked smut. This anatomical proof 

 places the fact of flower-infection on a sound basis (Fig. 6). Flower-infection 



experiments have also been carried out by the United States Department of 

 Agriculture, and in a communication, dated October, 1908, it is stated that 

 " During the last two years numerous inoculation experiments have been per- 

 formed with the loose smuts of wheat {Ustilago tritici) and loose smut of barley 

 {Ustilago nuda). In the case of both of these smuts infection takes plaee 

 only at the time of flowering of the host. The smut spores are easily carri'-d 

 by the wind, and as the wheat and barley glumes open for a &hort time during 

 the process of pollination, the spores readily gain entrance and infect the de- 

 veloping ovary. The smut-gerin then lives intraseminally until the grain 

 sprouts in the spring, after which it grows along with the host, and at Hower- 

 mg-time becomes evident as the well-known loose smut." 



4. Shoot Infection. 



The only method of infection recognised for a long time among the snmts 



was that of the seedling being attacked by the germinating spore attached 



to the seed, and this was known as Seedling infection. Next it was found 



that in American corn smut young and growing ]iortioiis might be attacked, 



is:,?. c 



