MICROSCOPIC GARDENING. 



15 



During the slow course of evolution of our ' knowledge of 

 soil, as investigations multiplied and improved, and as it became 

 more and more certain that a mere chemical analysis of a soil 

 taught far less as to its value than had hitherto been assumed, 

 it became more and more noticeable that soil is a complex of 

 much more than so many bits of rock and chips of rotting leaves 

 and wood : it teems with microscopic living beings — nay, it is, so 

 to speak, alive with living organisms. 



A thimbleful of garden-soil contains so many millions of 

 microscopic algae, fungi, bacteria, infusoria, and other living be- 

 ings, that the brain reels in the attempt to figure them swimming 

 in the films of water lining the interstices between the particles 

 of sand, slate, granite, clay, wood, straw, dung, bones, insects' legs 

 and scales, and other tiny bits of dead things, to realise that they 

 are consuming oxygen and giving out carbonic acid and other 

 excreta ; that they are living, growing, and feeding, and repro- 

 ducing, and in their turn dying, and that in the myriad turmoils 

 of their existence they are inducing changes in the soil, so con- 

 tinuous and so varied that in spite of their minuteness in detail, 

 the changes must be vast indeed in sum. 



After the fact had once been realised that the soil swarms 

 with living organisms, attempts were soon made to arrive at 

 some ideas as to their numbers and distribution. 



Shortly put, it was soon found that the greater numbers by 

 far are just beneath the surface, at a depth of a few inches to less 

 than a couple of feet, and that these numbers rapidly diminish as 

 we descend, till few or none occur at 3 to 6 feet down. In other 

 words, these soil-organisms predominate just where the principal 

 absorbing roots of our ordinary plants are at work. The 

 numbers differ in different soils : a sandy soil may have 

 only about 1,000 per thimbleful, where a garden-soil will 

 contain 10,000,000 or more, and the soil of a street up to 60 or 

 70 millions : they are also more numerous in summer than in 

 winter, and in moist warm climates than in dry cold ones, and 

 so on. 



Now the question at once suggests itself what are these tiny 

 beings busy about ; and how do their doings in the neighbour- 

 hood of the absorbing root-hairs affect the plants of our gardens, 

 fields, and forests ? For we cannot possibly suppose that they 

 exert no action on these. Microscopic gardening alone can 



