ge IOWA ACADEMY OF SCIENCES. 



Warrington found 37 ; Jordan"^ has also found several in the sewage of Boston 

 water supply. Prof. G. E. Patrick made an examination for the writer of eight 

 species; of these five were energetic reducers of nitrates to nitrites. This property 

 was not confined to facultative anaerobes. Sarcina lutea. Streptococcus cinnabar- 

 eus are both aerobic, and yet are energetic reducers. 



This field of bacteriology is a most fascinating and an important one. The 

 whole subject of decomposition of organic matter might well engage the attention 

 of many investigators. The results of Schlce^ing and Muentz on nitrification and 

 the erosion of rocks through the agents of bacteria, the brilliant achievements of 

 Winogradsky, Warrington and others on these questions should be brought to the 

 attention of agriculturists. These problems are important in the production of 

 crops, and may well stimulate tor a knowledge of things that seem hidden. 



Let us now consider the appropriation of nitrogen in leguminous plants. Leg- 

 uminous plants as renovators of our soils has been an established axiom in agricult- 

 ure for years, but it is only within recent times that this was properly accounted 

 for. Did not Boussingault show that plants cannot take up the free nitrogen 

 of the air through the leaves of plants? 



Scientists generally opposed Ville's idea that some plants have the power of 

 taking up free nitrogen, but after nearly half a century of investigation, the 

 world at large has come to accept his conclusions. The various phases of the appro- 

 priation of atmospheric nitrogen because of the nitrogen found in the tubercles, 

 and the symbiotic relation to the plants in question, has received wide discussion in 

 the agricultural and scientific papers. It is because the economic and scientific 

 phases are so important and interesting from practical and chemico-physiological 

 standpoints that they have been considered in this way. The practical farmer is 

 interested in the accumulation of nitrogen in soil through the decay of tubercles 

 and the appropriation of nitrogen by the plant. It makes his soil more productive. 

 The chemist and biologist are interested in finding out facts in regard to how this 

 is accomplished, the structure, form and relationship of the organisms in question. 



I presume most of you are familiar with the earlier work. At one time they 

 were supposed to be insect galls. Bivona"^ thought they were fungi and placed 

 them in the genus Selerotium. Tulasne, with his great knowledge of fungi, cast 

 them out of this group of plants. Later they were held to be normal structures of 

 the plants, "swollen lateral roots," "imperfect buds," normal structures of the 

 roots for the storage of reserve food material. Prof. Atkinson,"^ who has made a 

 most excellent summary of the investigations, reviews the status of the question in 

 three periods, early, middle and recent. During the middle period the preponder- 

 ance of evidence seems to have been to regard them as normal structures for the 

 storage of reserve food material, although the views of some authors were dia- 

 metrically opposed. Frank, who at first supposed them to be fungi, related to the 

 genus Protomtjces, established by De Bary, later entirely abandoned this 

 view and thought they were simply for the storage of proteid material. In this he 

 was supported by Brunchorst, Tschirchand VanTieghem. Worooin, Knyand others 

 held that they were living structures related to Plasmodium hrassicce. Later 



1121. c. 



113 Quoted by Atkinson. Contribution to the Biology of the organism causing legu - 

 minous tubercles, Bot. Gazette. Vol. XVIII, pp. 158, 226, 257, where there is a most 

 excellent bibliography. There is also a good review Dy Conn. Experiment Station 

 Record, Vol'. II, pp. 686-693. 



1141. c. 



