1915] 



APPEL— PHYTOPATHOLOGY AND SCIENTIFIC BOTANY 277 



flowers. This fact pointed out the way of control. The 

 problem was to kill one organism, the smut-fungus, within 

 another organism, the grain seed, without doing damage to 

 the latter. Jensen by his empirical work had demonstrated 

 that such a procedure was possible. The correct method of 

 control, however, could not be worked out because of the lack 

 of knowledge concerning the fundamental scientific facts 

 involved. In order to establish such a firm basis, I, together 

 with my assistant, Eiehm, studied the resistance of the smut- 

 fungi to external conditions, primarily to the effects of tem- 

 perature. When the mycelium was grown in water and other 

 substrata we demonstrated the fact that the thicker-celled 

 mycelium as well as the spores are more resistant to external 

 influences than is the vigorously growing mycelium. How- 

 ever, not only the smut but also the grain is more resistant 

 in the resting period than when germinating. Therefore, we 

 tried to bring the infected grain seed under conditions which 

 cause the fungus to grow and which at the same time do not 

 allow the seed to germinate. We succeeded in doing this by 

 allowing the seeds to remain for about four hours in water 

 at 25-30° C. If one then subjects the seeds to a temperature 

 at which the mycelium is killed but which does not yet induce 

 germination in the grain, it is possible to kill the mycelium in 

 the seed without injuring the latter. 



In these investigations the key to the so-called hot water 

 and hot air treatment was found, and it was then only a 

 technical problem to build apparatus with which the desired 

 results could with certainty be realized. For our conditions 

 in Germany this latter problem has also been solved. We 

 have constructed several pieces of apparatus of this sort, and 

 the treatment of grain against loose smut has been introduced 



on many farms. 



But the smut-problem has not been solved for all cases. 

 This is especially true in the case of the stinking smut in the 

 United States. This disease is of the greatest importance in 

 the wheat districts of Idaho. In Germany Tilletia Tritici is 

 spread by the seeds and is controlled by seed disinfection. In 

 Idaho it occurs so generally in the soil that disinfection is 



