SOCIETY OF CENTEAL ILLINOIS. 187 



tive test indicating the presence of nitrites, and also in a less degree 

 that of nitrates. 



On the seventh morning both nitrates and nitrites were very 

 abundant, undoubtedly due to the action of the bacteria on the nu- 

 triment solution, and these plants grew on in a flourishing manner, 

 having seemingly all the conditions of growth fully satisfied. 



In marked contrast to this pot was another started at the same 

 time, under precisely similar conditions as to having it free from 

 organisms: and to maintain it free from contamination it was -kept 

 under glass, with ample provision for circulation of air and for sup- 

 plying nutrient material. The air admitted was passed through 

 tubes filled with cotton, to prevent the entrance of organisms, and 

 the water and nutrient solutions were disinfected by heat before 

 being applied. By this means, all organisms were excluded. 



On comparing this experiment with the one just described, we 

 find them seemingly equal through the period of germination, and 

 the first one or two days' growth. On the fifth day a marked differ- 

 ence is noticed, those without organisms being pale and drooping. 

 An effort was made to revive them by adding a supply of nitrates to 

 their food. On the following day, the plants seeming to be in a still 

 worse condition, a liberal supply of organisms was added, but with- 

 out effect. 



In this experiment no nitrates could be detected in the drainage 

 water. This experiment then, seemed certainly to point to the fact 

 that the plant, to grow, must have present these organisms. 



As still further bearing on this point, another of the experi- 

 ments may be here noted. 



Some grains of sweet corn were being grown in sand, and 

 watered with a 1-100 per cent, solution of corrosive sublimate; that 

 is one corrosive sublimate to 10,000 of pure water. This served to 

 keep the pot free from germs, without destroying the vitality of the 

 corn. However, the sprouting was feeble, especially as to the devel- 

 opment of root, which, after pushing out an eighth of an inch, 

 stopped growing entirely. The plumule continued a little farther 

 and stopped. By the sixth day the conditions had become favorable 

 for the presence of organisms in great number. Simultaneous with 

 their apj)earance we find numerous fine roots starting, the ui)ward 

 growth of leaves starts vigorously, and nitrates appear in the drain- 

 age water. Here, again the organisms seem to play an important 

 part, but whether their presence is needed for anything more than to 

 supply the nitrates, and whether the plant would thrive irith the 

 nitrates, and icithout the organisms, is still a matter of question. 



None of the experiments so far have been conclusive on this 

 point, though the weight of evidence seems to indicate the necessity 

 of the presence of the organisms, either in close proximity to or upon 

 the roots, as feeders to provide for the delicate root filaments the 

 essentials to the life of the plant. 



