1896.] Vegetable Physiology 141 



abundantly infected with smut conidia. Of the 50 plants thus treated 

 one died at the end of 4 weeks from a smut pustule on the axis, and 

 the rest developed without any appearance of smut. Another experi- 

 ment was undertaken with 150 seedlings still further advanced, the 

 conidia being sprayed upon them, but this also gave negative results. 

 No germtube penetrations could be found and no smut appeared upon 

 any of the plants. These results led to a good deal of speculation and 

 finally to the following experiments : The first of these was with plants 

 a foot high, having a well developed cornucopia-like summit formed by 

 the closely wrapped bases of the large outer leaves. One hundred 

 plants were selected and into these cornucopias a nutrient solution con- 

 taining smut conidia was injected. They were covered with straw mat- 

 ting five days to keep off rain and then freely exposed. On the tenth 

 day, as growth continued and the infected parts were pushed up into 

 sight, there was a changed appearance. The parts of the leaves touched 

 by the infectious 6uid were paler than the upper noninfected parte ami 

 suggested chlorosis. This appearance was visible in different degrees 

 on all the infected plants? Already there were slight appearances of 

 pustules and within a day or two they became very distinct, finally 

 covering the whole infected surface with a smutty crust. Scarcely one 

 of the male inflorescences escaped and the axis between the leaves was 

 also smutty in so far as the infective material could reach it. Not one 

 of the hundred plants escaped infection, the youngest suffering most. 

 For the next experiment younger plants were selected, i. e. those about 

 six inches inches high. In many of these the cornucopia was not well 

 developed and allowed the infectious fluid to run out and waste and 

 the infection miscarried. All, however, that were large enough to re- 

 tain the conidia were killed outright by the development of smut pus- 

 tules, the plants twisting and curving in all sorts of shapes and fre- 

 quently wilting before the smut spores were mature. The third ex- 

 periment was with plants li feet high. Here the cornucopias were 

 wide open and took in large quantities of the infectious fluid, which 

 penetrated deep into the heart of the plant. After three weeks the 

 male inflorescences appeared, but in only six plants out of 50 could any 

 symptoms of smut be found and upon these the pustules were small and 

 scattering. On the leaves there were wrinkled, white spots which, how- 

 ever, did not develop into smut pustules but subsequently became green 

 and nearly normal in appearance. Scattered smut pustules were found 

 on the axis at the base of the internodes in 7 cases, and the effect of the 

 fungus was also visible on some of the upper blossoms which remained 

 white and dried up without developing. Aside from these scattering 



