68 MASSACHUSETTS HORTICULTURAL SOCIETY. 



which does not naturally contain these beneficial organisms. 

 Practical farmers have realized for years that some parts of a 

 field would produce clover or alfalfa successfully, Avhile others, 

 which seemed to be in fully as good condition and were as care- 

 fully cultivated, failed to produce a good stand. Many times this 

 condition could be remedied by the addition of lime or some 

 careful cultural method, but it was often found that the roots of 

 the plants which failed showed no nodules and it was evident 

 that the nodule-forming bacteria did not exist in that spot. For 

 this reason it became necessary to devise some means of arti- 

 ficially introducing into the soil the nitrogen-fixing bacteria. 

 Naturally, the easiest and simplest way of accomplishing this was 

 to transfer soil from a field which had produced nodule-bearing 

 plants and by this means introduce the bacteria into the soils 

 which were devoid of them. 



Transferring soil from one field to another on the same farm is 

 a comparatively simple and inexpensive process, but when, as is 

 often the case, thousands of pounds of soil have to be shipped 

 hundreds of miles, the operation becomes more difficult. It is 

 also a fact that certain diseases of plants, the spores of which 

 remain in the earth, are widely disseminated by such means of 

 attempting to introduce nodule-forming bacteria, and in some 

 cases where the disease causes great damage to leguminous crops, 

 it has become necessary to abandon altogether this method of 

 inoculation. There is also great danger of introducing objec- 

 tionable weeds and insect pests, so that if any better means of 

 inoculating the soil could be devised, it would certainly be de- 

 sirable. It should be understood, however, that many cases of 

 inoculation by soil transfer in this country have been eminently 

 successful, and, although the percentage of failures is greater 

 than is usually supposed, there is no question but that much good 

 has been done by this means of inoculating the soil. 



A number of years ago a German botanist conceived the idea 

 of bringing about inoculation by the means of pure cultures. 

 This was to be accomplished by isolating from the nodule the 

 right organisms and then transferring to tubes containing a me- 

 dium which would enable them to multiply rapidly. There was 

 no difficulty in obtaining these pure cultures, and within a short 



