16 TRANSACTIONS AND PROCEEDINGS OF THE [Sess. Lxi. 



Frank and Prillieux, in 1879, described them, and 

 regarded tlieni as due to the attack of a parasitic fungus. 



Schindler, at the same time, studied them, and came to 

 the conchision that the fungus was associated with the 

 leguminous plant in a symbiotic manner ; and Brunchorst, 

 some years later (1885), described the nodules as store 

 chambers, where the plant laid up a store of albuminoid 

 matter which it utilised during ripening. 



This view was suggested before by De Fries (1877), 

 who held that the nodules were absorbers of nitrogen, 

 which the plant utilised for making its albumen. 



Schindler, in 1885, thought they were connected with 

 the plant in a symbiotic manner, and that their function 

 was to absorb nitrogenous organic matter from the soil. 



Ischirch thought that these nodules grew best on soils 

 that were poor in nitrogenous matter, and that they not 

 only stored up nitrogen for the use of the ripening plant, 

 but that they also went back partly to the soil and enriched 

 it in nitrogenous matters also. 



It was when observations and views of that kind were 

 current that Hellriegel and Wilfarth published an account 

 of their experiments. 



These experiments commenced, as I said, in 1883. He 

 found that when he grew leguminous plants and gramineous 

 plants, say peas and oats, in the same soil — a soil consisting 

 of sand, to which nutritive solutions were added — that the 

 oats grew and flourished in proportion to the quantity of 

 nitrate of soda supplied in the manure. When the amount 

 added was small, the growth was small ; when the amount 

 was doubled, the growth was doubled ; when the amount 

 was trebled, the growth was trebled; and so on, until 

 sufficient was added to produce a full crop, when, of 

 course, the further addition of nitrate produced an ever- 

 diminishing increase. It was quite plain that the oats 

 derived their nitrogenous food precisely from the nitrate 

 of soda provided for them. The peas, on the other hand, 

 grew in ([uite a capricious manner; showing that they 

 were not dependent for their nitrogenous food supply on 

 the nitrate of soda, or at least not on it alone. As a 

 matter of fact, the pot which got least iiitrate grew the 

 largest plants. 



