CONTRIBUTIONS FROM THE WISLEY LABORATORY. 



393 



The plants on all the plots were well supplied with nodules, and there 

 was no noticeable difference in the number of nodules on those inocu- 

 lated as compared with those that were not. 



The results as set forth above call for little comment. They are 

 obviously not in favour of inoculation, but taking into consideration the 

 results of plots 1, 7, and 15, which received similar treatment, as did 

 2 and 11, which show a gradual falling off from one end of the ground 

 to the other (fig. 139), it is equally plain that the reduction of crop which 

 characterizes the plots towards the southern end cannot be attributed to 

 inoculation. 



A comparison of the yields of the plots which were inoculated with 

 those which were not (which included the largest and the smallest crops) 

 is instructive in this connexion. 



TABLE B. 



Treatment Average yield 



Not inoculated. 



Plots 1, 2, 7, 11, 15 782 grs. 



Inoculated once. 



Plots 3, 4, 5, 8, 9 787 grs. 



Inoculated twice. 



Plots 6, 10, 12, 13 . . . . . 727 grs. 



Inoculated three times. 



Plot 14 ....... 666 grs. 



These averages show that the diminution of the crop was due rather 

 to the position of the plots than to the inoculation. 



A series of cultures made in pots with the same soil showed similar 

 results. 



Wide Disteibution of the Nodule Bactekia. 



In connexion with the question of soil inoculation for leguminous 

 plants it seemed of some interest to find to what extent organisms 

 capable of forming nodules on peas and beans were distributed in the 

 soils in various parts of the Wisley Garden and in a few other places on 

 different formations. The results of these tests are shown in Table C 

 below. 



In order to minimize the risk of contamination with bacteria from 

 other sources as far as possible, the soil (so far as the Wisley soils are 

 concerDed) was dug out with spades thoroughly washed with a solution 

 of mercuric bichloride and carried to the Laboratory in clean boxes. It 

 was then placed in pots that had been washed and kept after crocking in 

 steam at 98° C. for an hour, care being taken that the soils were not mixed. 

 The seeds were soaked for half an hour in carbon bisulphide to kill any 

 adherent bacteria, and then, as soon as the disinfectant had evaporated, 

 they were sown in the pots prepared for them. The pots were covered 

 with cotton wool and they were watered with water recently boiled. The 

 cultivations were made in duplicate. Precipitated chalk was added to 

 the soils which were poor in lime. 



