33 



20. Rice or l^'~an (Facher) o O 



21. Black Barley o o 



4. Erfurter, white o o 



10. Kallina 0.5 0.5 



15. Naked, 3 forked, 3 rowed 2 2.5 



The discovery that loose smut does not disappear from the fields of grain in spite of 

 sterilization indicates convincingly that, besides the infection of the young germinating seed- 

 lings, still another form of infection must exist for our smut fungi, from which an explanation 

 could be deduced for the fact that smutted plants grow from sterilized seed grains. This fact 

 has only now been made clear and in such a natural and simple way that every agriculturist 

 must be interested in learning that the smutted individuals of a field are the direct centres of 

 infection. The germs of disease are carried directly at the time of blossoming from these dis- 

 eased plants to the healthy ones. 



But this explanation would be only one-sided and not very satisfactory for the agricul- 

 turist, if it were not possible to set up a different method for fighting the appearance of smut, 

 instead of considering sterilization of the grain infallible which had been universally assumed to be 

 effective. .And what can be the nature of this new protective means of preventing smut? Clearly 

 it is no other than that the field be prepared only with healthy seed taken from fields free from 

 smut and that thus the struggle against smut be undertaken not positively but negatively. It 

 is scarcely practicable to pull up smutted plants from the field in order to prevent blossom infec- 

 tion. Seed must be chosen from fields free from smut and thus prevent the sowing of seed 

 grains already attacked by the smut infection. Pure seed from fields free from smut must from 

 nutv on be the means of ending the agriculturist's struggle against smut. If this is universally 

 and carefully carried through the appearance of smut must of necessity decrease gradually and 

 cease entirely so far as forms are involved which are infected in the blossom. 



With this, our investigations of blossom infection in the loose smut of wheat and of 

 barley are concluded for the ])resent. A subordinate question must not remain unanswered 

 here, — which involuntarily becomes obvious, — the question namely, whether the smut germs of 

 infection found in seed infected in the blossom can remain capable of development for several 

 years. The solving of this problem strengthens at the same time the certainty of the fact that 

 infection takes place in the blossoms and that the germs of infection exist latently in the rii)ened 

 seed. 



A part of the wheat and barley seed which had been harvested was retained and used 

 for ex])eriments in succeeding years. New sov/ings were made, once of wheat and once of barley, 

 from the seed grain from which in the first year, after successful sterilization, the highest per- 

 centage of smutted plants were produced, but which had lain dormant two years. The seed 

 was sown with all possible care as given above and, from the grain which proved itself still 

 capable of germination, strong plants were grown which, at the time of blossoming in the second 

 year, gave the same picture of smutted experimental fields as described in the first years and 

 reproduced in figs, i and 2. All the plants in the separate experiments were smutted. By 

 means of these last experiments it ivas proved to be a fact that the germs of infection latent in 



