8 4 TRANSACTIONS AND TKOCEEDINGS OF THE [Sess. lxii. 



It inny be objected to the results of Stocklasa's experiment 

 that they do not explain why it is that leguminous plants 

 should be the only ones able to derive benefit from the 

 nitrogen brought to the soil by the algie and bacteria 

 referred to. That question Stocklasa answers in a some- 

 what unexpected manner. He gives tlie result of five years 

 experimenting with buckwheat {PoIy(junv.rii fagoii2)n(m), a 

 plant far removed from the LeguminoStC, and shows that it 

 also has the power of assimilating atmospheric nitrogen, 

 especially when grown in soils that are fairly well supplied 

 with nitrogenous manure. 



Into the details of that experiment time will not permit 

 one to enter, but the results are shortly as follows : — 



100 plants grown in a sterilised soil assimilaterl of 



atmosjjheric nitrogen .... *lo8 grams. 



lOU plants in an «»,sf(';77/NeJ soil. . . . 1'378 ,, 

 (That is to say ten times as much.) 



10<) plants grown in a slej-ilised soil to which 



ammonium nitrate was added as a manure 3 "3 85 ,, 



lOo plants in an imstcrHised soil similarly 



manured ....... 6 "09 ,, 



This experiment, l^esides putting on record the fact that 

 ])lants other than leguminous ones can utilise atmospheric 

 nitrogen, shows how greatly dependent for that faculty they 

 are upon the lowly organisms that inhabit the soil in wliich 

 their roots are ramifying. 



Time will permit me to do no more than refer in a few 

 words to an experiment, which, through the kindness of 

 Professor Balfour, and with the valuable assistance of Mr. 

 Harrow, I was able to carry out at tlie Botanic Garden 

 last summer. The experiment was only a provisional and 

 tentative one, as a prelude to one which I liope to try next 

 summer. 



A soil made of a very poor subsoil, about three feet below 

 the surface, which had been laid bare during the building 

 improvements going on in the Garden, was chosen on account 

 of its poverty in nitrogen, and it was mixed with sand in 

 equal amount. To this was added a sujjply of fertilisers, 

 viz. phospliate and potash salts, but no nitrogen. This was 

 filled into three sets of pots, measuring eight inches across, 

 and containing about five pounds of soil each. One-third 

 of the pots was left without further manure, and the other 



