No. 4.] CLOVERS. 429 



needed moisture at critical times, enormous crops of clover may be 

 produced. 



4. The Co-operation of Bacteria is essential. — One of the most im- 

 portant discoveries of recent times is the now generally known fact 

 that the presence of certain bacteria living in symbiotic relations with 

 the clovers and other members of the clover family, and found in 

 nodules on their roots, is essential in order that these plants may draw 

 upon the air for nitrogen. The nodules which in the case of clovers 

 indicate the presence of suitable bacteria are whitish, more or less ellip- 

 tical bodies, of about the size of the head of a small pin. These grow 

 singly or in small clusters, mainly on the smaller roots. They can be 

 readily found by taking up clover plants grown under proper condi- 

 tions, with care not to break off too many of the small roots. Bac- 

 teria, as is generally understood, are plants. They are very minute. 

 The bacteria themselves are the veriest dust of the dust. As might 

 be supposed, therefore, they appear to be very widely and freely dis- 

 seminated, and probably through the air. The slightest currents of 

 air must carry them. The dust from a freshly turned clover sod must 

 contain countless millions of them. In certain quarters it has been 

 urged that failures to produce good clover are frequently due to the 

 absence of suitable bacteria, or to their presence in insufficient num- 

 bers. Certain experiments with sterilized soils in Amherst indicate to 

 the writer that clover bacteria are everywhere ; and it is not his belief 

 that failures to produce satisfactory crops of clover in this State can 

 often, if indeed they can ever, be attributed to the cause under con- 

 sideration. The writer has never seen a case where, if a soil be brought 

 into proper condition as to drainage and freedom from acidity, and 

 well stocked with phosphates and potash, clovers have failed to grow; 

 and he has never observed clover plants in any locality and failed to 

 find abundance of nodules on their roots. It is, however, of course a 

 possibility that there may be localities where it will pay to inoculate 

 the soil designed for clover with suitable bacteria. This inoculation 

 may be carried out in either of two ways. First, soil from a locality 

 where clover thrives and where the nodules are known to be abundant 

 may be scattered over the field where the clover is to be sown, and 

 immediately harrowed in. Five or six hundred pounds of such soil 

 per acre will be sufficient. Second, a culture of the proper species of 

 bacteria may be used in accordance with directions which will be 

 furnished with it Such cultures may now be procured either from the 

 United States Department of Agriculture in Washington, or from 

 private dealers. These cultures are known by the name of nitro- 

 cultures; but, as each species of the clover family must have its own 

 species of bacteria, it is necessary in ordering to name the plant for 

 which the nitro-culture is needed, as well as the area. 



The United States Department of Agriculture first sent out cultures 

 in dry form, in small packages containing dried cotton and chemicals, 



