25 



was not realised, and the deficiency could not be remedied by 

 merely adding more of the organisms. 



Further, it was shown that many of the cultures sent out to 

 farmers died on the way, so that the material used for inoculation 

 was useless. This difficulty has been overcome by devising means 

 whereby the organisms could be transported alive. The need for 

 fresh, active stocks of the organisms available for farmers at short 

 notice has been met by devising a medium in which the organisms 

 grow much more quickly than in the older media. 



The organism cannot flourish in soils having too great a 

 degree of acidity ; a usual limit corresponds with the pH scale 

 number 6.0. 



A much more difficult problem is being attacked in the 

 Bacteriological Department. The organisms were found to pass 

 through a life cycle including motile stages in which they can 

 travel to the plant, and non-motile stages in which they 

 cannot. The non-motile stage can, however, be made to 

 change into the motile stage by certain treatments, especially 

 the application of phosphates; this is no doubt one reason 

 fqr the remarkable effect of basic slag in increasing the 

 growth of clover on certain soils. Messrs. Thornton and Gangulee 

 have measured the time required for the organisms to assume 

 the motile form in the soil, and the rate at which they then spread 

 through it. On the basis of these various facts, Mr. Thornton 

 has been able to devise a method of inoculating which ensures 

 an earlier commencement of spread of the organisms in the soil, 

 and therefore a better chance of infection of the roots, than in 

 any method previously tried in this country. 



The Research Committee of the Royal Agricultural Society 

 has made a grant to Rothamsted which is allowing extensive 

 trials to be carried out at some thirty centres scattered 

 throughout England to test the value of the method for 

 lucerne. It is too soon to speak definitely about the results, 

 but already inoculation has proved of considerable value 

 in new districts where the crop has not previously been grown, 

 and it has in places doubled the growth in the first year as com- 

 pared with the uninoculated plots, besides giving vigorous plants 

 which promise to survive and come out in full strength in the 

 summer. Meanwhile the purely scientific study of the organism 

 and of its relation to the plant is being steadily pursued with 

 the object of getting further information. Exceptions and difficul- 

 ties will inevitably arise as soon as farmers adopt inoculation as 

 a general practice, and the surest way of minimising the resulting 

 losses and inconveniences is to obtain the fullest possible know- 

 ledge of the whole process. 



Two investigations have been carried on which cannot fail 

 to have important bearings on the practical problem. The first, 

 which is still in hand, is concerned with the influence of straw 

 on the formation of nodules. Attention was directed to this by the 

 observation that farmyard manure is more effective in increasing 

 the growth of clover than any dressings of artificial manures 



