56 



the plant in the first emlDryonic points, continuing its growth with the maturing of these, until 

 at the end of development they pass over in the blossoms to the formation of spore masses. 

 The adjustment of the parasite to the host plant is the most complete possible. Nothing at 

 all of any appearance of disease is to be seen in the course of the whole development of the 

 host plant up to its complete maturity. In fact the phenomena are constantly repeated, that 

 the host plants attacked by fungi develop more quickly and luxuriantly than healthy ones and 

 that spore masses have appeared in them when the inflorescences are just beginning to show 

 in healthy plants. One is tempted involuntarily to believe that parasites living in infested 

 host plants can exercise an influence favorable for a quick and complete development. These 

 external circumstances make somewhat desirable the choice of these experimental plants as objects 

 for the decision of the question whether fungus threads living parasitically in their host plants, 

 here especially smut fungi, are able in connection with these to assimilate free nitrogen and 

 thereby be in a position to cause a more luxuriant nutrition of the host plant. 



L'p to this point only one impediment had been found in using host plants attacked by 

 fungi for this kind of experimentation and this lay in the circumstance that in the experiments 

 it was never certain whether the plant under experiment had been attacked by smut and whether 

 one was actualy working with smutted experimental objects which alone could bring about a 

 decision of the question. This impediment has now been overcome by the continually improved 

 methods of inoculation of host plants with smut fungi. It became possible in the different millet 

 forms, — Indian millet, Panicum and Italian millet, — to produce with certainty infected germi- 

 nating seedlings for the experiments and just as surely to use seed obtained from blossom infec- 

 tion which from experience was seen to produce only smutted plants. 



The natural method of arranging the details of the experimentation works out of itself, — 

 as Hcllricgcl had planned it. According to him, sterilized absolutely pure vitreous sand was 

 saturated with mineral nutrient solutions, but without any nitrogen compounds, and then put 

 in glass jars, which, sunken in soil, were provided with ojjenings and a covering of gravel for 

 purposes of ventilation. In this substratum the freshly infected germinating seedlings of the 

 three millet forms, — Indian millet, Panicum and Italian millet, — were planted in separate pots, 

 from 3-5 specimens being put in each. The single plants were weighed on the decimal scales 

 at the beginning of the experiments and daily loss through evaporation was rejjlaced with dis- 

 tilled water free from nitrogen. For comparison, pots were arranged in the same way as those 

 described above, only with a corresponding addition of a nitrogen compound in the form of 

 calcium nitrate. In these parallel experiments the same number of experimental plants, that is, 

 germinating seedlings, were planted in each pot. The experimental plants were then placed under 

 protection in the propagating house and in good weather carried into the open air on a truck in 

 order to expose them to the direct sun. Thus, with this method of setting up the experiments, 

 sources of error could not creep in. The transplanted seedlings in both series of experiments 

 grew without clifficulty in the vitreous sand and in the first eight days showed scarcely noticeable 

 differences. Then after the exhaustion of foodstuffs in the germinating seed, the lack of nitrogen 

 on the one hand and the action of the nitrogen compound on the other, first made themselves felt 

 and led to an even more striking phenomenon. In the next four weeks the pots without nitrogen 



