334 



some of the combinpfl nitrogen acciunulated through ag«'son the surface 

 of the globe; and also from a practical point(>f view, since, especially in 

 troi»ical countries, such plants yield many inijtortant food materia^><, as 

 well as other inrlustrial products. 



Root tubercles and acquisition of nitrogen by legumes — inoc- 

 ulation experiments in field culture, Hellriegel and Wilfarth. — 

 In the account given in the jiresent vohune of the Experiment Station 

 Record, p, HOT, of the meetings of the section for agricultural chemistry 

 of the German Association for the advancem<Mit of science at Halle, in 

 September, ISOl, nu-ntion was made of a s(>mewliat informal report by 

 Professor Jlellriegel, director of the experinuMit station at liernburg, 

 on the continuation of his investigations u])on root tubercles and the 

 fixation of atmosjiheiic nitrogen by ])lants. 



It will be remembered that the experinuMits of Professor llclhiegel 

 have been made mostly by the nirtlmd (»f sand culture, which lie has 

 developed by many yeai's of experimental incpiirN . and that althongh the 

 acquisiti(»n of huge (piantities of atniosi»heric nitrogen by leguminous 

 plants li;id ItccH dfiiionstratcd l>efbre Hellriegers work at Bernburg on 

 this snltject was undertaken, yet it was thr<»ugli th<>se investigations 

 that the connection between root tnln-rcles, bacteria, and the fixation 

 of nitrogen was first found out. F»'w discoveries in biological and agri 

 cultural chemistry have brought (»r]>romise to bring such an important 

 train of results as this. The develoimuMit of tin* subject ]ty various 

 e\]»eii!nents has been recoriled from timetotimein th«' Hecord (vols, t, p. 

 I'.M; II, p. «IS(;. and ill. pp. rid. 1 Km. Tliiongli tin- (•onrlesy o| rroft'ss«tr 

 Hellriegel and of Dr. Willaitli. wiio has been assucialed with him in 

 these in\ estigalioiis, the follow ing resmiH' of their latest I'c-^nlts, pre- 

 ceded hy a Inief recapitulation of the earlier work at 15ernl»nrg. has 

 been I'liniislird Ity the hit ter geiit leniaii lor puldication in the ItiTord: 



l're\ions iuN cstigations had shown that while the legnmiiions plants 

 can a\ ail tliemselv«'s of the free nitrogen of the air, they can tlo this 

 on]> when certain kinds of hacteiia have entered them and caused the 

 ]>rodu«'tion of the root tnb»Tcles chara<teiistic of tin' legumes, brgu- 

 minous i>Iants which are «ultivated in sterilized media and kept fre<* 

 from bacti'ria during their grow th, so as to jtreveiit this symbiosis, and 

 which in conse()uence ha\'e no tubercles, do not acrpiire nitrogen from 

 the air. Thus cult ivatcd tlicy l»elia\t' like tlie non-leguminous plants, 

 which, as experiments ha\i' ic]»catedl\ shown, can not assimilate free 

 nitrf>gen. 



During the last few years a series of ex])crinients has been going on 

 at r>ernbnrg with legumes which have been kept under «'onditions of 

 sterility. These exjx'riments hav«' brought out the fact that tlie legunies 

 thus kept sterile not (Uily failed to fix nitrogen, asjust stated, but akso 

 when tlu'v were well su]>]>lied with other food and dejjrived of nitrogen 

 comi)ounds in the medium in which tin'y grew, remained in a starved con- 

 dition, though they grew well wlicu nitrogen compounds were supplied. 



