i6 



For the sake of brevity, the designation "cylinder infection" will be used in the following 

 for the kind carried out in glass cylinders of tested size by means of the disseminating apparatus 

 already .described. 



The second kind of infection, which supplements most naturally the one already given, is 

 infection by artificial introduction of the smut spores in the separate blossoms, which have just 

 opened or are ready to blossom. This kind of infection by artificial introduction of the smut 

 spores in the separate blossoms necessitates naturally more or less forcible attack upon them. 

 The smut spores are most expediently carried over into the interior of the blossoms by means 

 of a fine brush and here placed upon the stigma and ovary. To carry out this infection most 

 skillful hands are needed, which will not injure the further opening of the blossoms but easily 

 and surely, by means of the brush, will carry the smut spores over on to the stigma and ovaries 

 in the interior of the blossom. We have used with advantage the hands of skillful women. After 

 a little practice they have carried out the manipulation of inoculation with relative delicacy and 

 sureness. Since the infection is here carried out on separate blossoms it is more certain than in 

 cylinder infection and the results are also still more assured by the cutting off and removal of 

 all non-infected blossoms. If this is done with the greatest care and skill, it may be assumed, 

 that each blossom must be infected and that each ovary will be attacked by the germs of infection. 

 However, we find here a number of sources of error which are as natural as they are pertinent. 

 If separate blossoms are passed over rapidly in this infection a rather considerable source of 

 error is given for the later per cent of smutted plants, since only a limited number of blossoms 

 of a head may be infected at the same time. The second source of error is encountered if all 

 non-infected blossoms are not removed. Of course in this form of infection the secondary points 

 may be considered as disturbances which are given already under cylinder infection. 



From this it is easy to understand that in infection of separate blossoms the result can 

 be complete only in fortunate cases and that a corresponding loss must be shown in all those 

 experiments where cases of error may have crept in. In any case infection of the separate blos- 

 soms is disproportionately surer and more effectual than that of cylinder infection, even if it is 

 inferior to this in the artificial introduction of spores here necessary for infection. 



A further circumstance is of especial value for the success of blossom and cylinder infec- 

 tion. This lies in the freshness of the infection material, which in any case must be taken 

 directly from the field and if possible should be taken from the same field for the infection of 

 the plant. 



Doubtless the methods of infection here used can be further and better improved. The 

 results given below prove, however, that they are reliable and guarantee a relatively high grade 

 of effectiveness. 



Besides infection of the blossoms, infection of the young seedlings must be introduced in 

 this same experimental field. It was thought formerly but erroneously that infection would succeed 

 only on young germinating seedlings. In the same way it would now be erroneous to assume 

 that, in experimental plants, blossom infection is the only effective one. Both possible means of 

 infection should be kept in sight. First, infection of the young seedling; second, in the blos- 

 som. It is very possible that in the same plants both forms of infection can exist side by side. 



