Pkoo. R..V. Soc. Victoria, 25 (N.8.). Vr. II.. 1912. 



Art. X\MI. — On Ihr Cross I nocnl dl in n nj the Rool Tnhfrrh- 

 lincli'i-iii iijtoii tilt' Xatir/' uiul iha (' ulthnlcjl L^fJUiiii- 

 iiOsne. 



PKKI.miNAin' C'(lM\rLNICATION- 



A. .1. EWART, D.Sc. Ph.D.. F.L.S. 



(Professor ..f l{i.t,iiiy aii.l Plant Pliysioloiiv in tlu- University of Melbourne), 



AM) 



NORMAN THOMSON. B.Ao.Sr. 



((inv.-riiuH lit He-soai^'li Bursar. Mejbourn«' Univer.sity ). 



(Witli riate XIV). 

 Read sth .Aut^u.-^t. I!tl2. 



Introduction. 



If the roots of am' leLinmiiious plant are examined, there will 

 always be found ceitaiu little round "rowths attached to them; 

 these are known as nodules or tuliereles, and contain countless 

 numbers of bacteria. It is calculated that one such tubercle of an 

 average size (that of a matcli-hoad') would <-ontain from ]()(! to l(l(i(l 

 million bacteria. 



It has been found that the tri-oAvtli of any leguminous crop sown 

 in certain new sandy oi- heathy ground, will receive a decided 

 impetus if soil from a field in whicli this same crop has been 

 recently grown is scattered over it. either before or after sowing. 

 This is due to the introduction of this bacterium Bacilhix radicicola 

 ('Beyerinck') present in the soil, which causes the formation of the 

 nodules upon the roots, entry into M'hich is trained through tho 

 root hairs. Tn these nodules the hacteiia exercise their power of 

 fixing free nitrogen from tlie air, and passing it on to host plants 

 in forms it can utilise as nitrogenous food supplies. 



The Problem. 



There is a difference of opinion as lo whether inoculation can bo 

 tarried out on any one plant by the bacteria from tlie tubercles of 

 that plant only, or from any other plant of the same o^enus, or 



