31 



further, in order later, at the time of blossoming, to cause, as if by a stroke of magic, the appear- 

 ance of spore masses in the plant ivhieh, until then, had seemed healthy. The adaptation of a 

 parasite to its host plant appears here with a completeness not known in any other case in the 

 plant kingdom. Infection e.vtends back to the first embryonic parts of the young plant and the 

 appearance of disease becomes externally noticeable only in the second vegetative period in the 

 last stages of development. 



One would naturally think this inheritance, if the infection of the blossoms were not 

 proved with certainty and traced back to the time of the infection and fruiting of the embryonic 

 parts of the young embryo in the ovary of the blossoms. These facts, as notcivorthy as they 

 are important for the biology of smut fungi from a purely scientific side, adjoin the not less 

 important results zvhich are furnished by blossom infection for the practice of the agriculturist, 

 that is, for the struggle against smut fungi. 



It has been definitely proved by blossom infection that smutted individuals in the blos- 

 soming grain field form the centre of infection for the plants and of the further distribution 

 of the smut. The spores are disseminated as dust from the spore masses of the plants attacked 

 and are driven by the zvind directly on to the bio ssoms of the surrounding plants. They thus get 

 directly into the blossoms and on the stigma, ivhcre they infect the young ovary, susceptible to 

 infection. Only in the following year, however, do the phenomena of smut develop from the 

 seed thus infected as we find them in the fields. 



Formerly smutted plants had been observed attentively only from one point of view. It 

 was thought then that the smut spores were driven on to the surface of the surrounding grain 

 and on the soil, and that infection in the soil came to full maturity in the germs of the seed only 

 subsequently and only in them. The possibility of blossom infection, in which smutted plants 

 represent a direct and immediate centre of infection for the surrounding healthy plants, had not 

 been considered at all, nor especially that the seed already harvested could have been attacked by 

 germs of infection from the preceding blossoming period. 



In connection with the assumption of an exclusive infection of young germinating seed- 

 lings it was the firm belief that the struggle against smut could be successful only if the seed 

 with the spores clinging to its outer surface was disinfected ivith stcrilir:ing material, thus killing 

 the spores on this surface. Of what value is disinfection and sterilization of the seed grains now 

 if the grain is infected in the blossom? Evidently none at all. It is not necessary to kill the 

 spores clinging to the outside by sterilization ; for, as we have proved, they do not penetrate 

 into the seed. The germs of infection existing in the seed, which had penetrated at the time of 

 blossoming, can not, however, be killed by sterilization. This disinfection is only an external 

 one. Sterilization is therefore useless for the forms of loose smut in zvhcat and in barley. It has 

 already been shown that sterilized grain infected in the blossom has produced entire fields of 

 smutted plants. 



The fact here made clear that smutted plants grow from sterilized seed of wheat and of 

 barley is in itself not new. It has been known to the practical agriculturist for a long time 

 from experience, but its correct explanation had not been found. Further, investigations were 

 directed into a wrong channel, since it was always assumed that the form of sterilization was 



