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PART V. WORKING STAGE. 



to fifty times more abundant, wide, studiously varied, and dis- 

 criminating than it is at present outside first-class scientific 

 enquiries. Luther Burbank's surprising successes in improving 

 and transforming fruits and flowers, which have gained him the 

 title of the wizard of California, are largely to be traced to his 

 observations extending frequently to tens of thousands of spe- 

 cimens and over a long period of years. 1 Darwin was inde- 

 fatigable in varying his experiments : "Wherever it was possible 

 in his experiments, he varied the amount of a cause in order 

 to note the proportionate variation in the amount of the effect ; 

 and where he had to depend upon observation alone, he made 

 strenuous efforts to connect extreme instances by gradations 

 of character." (Frank Cramer, op.czY., p. 56.) 



The local inter-relations between plants emphasise the need of wide, 

 varied, and discriminating observation. The botanist offers us here a 

 singularly felicitous picture. "The series of different kinds of plants 

 playing 'follow my leader' into the fresh water ponds is another good 

 illustration of the power of the unaided plants to change the nature of 

 a given spot. Into the open water of a mere or pond, with its minute 

 flora of microscopic algge, push out the underground rhizomes of the 

 Phragmites reed and the Bulrushes. They send up tall shafts with leaves 

 and flowers, and in the autumn these die down, and the half rotting and 

 fibrous remains are tangled together with the roots and rhizomes, and all 

 tends to catch any further fragments or detritus that is drifting in the 

 water. Gradually, by this means, the reeds collect a soil which tends to 

 make the edge of the pond shallower, so that the Bog-Bean and other 

 shallow water plants can come in and help in the work till so much soil 

 is accumulated that the water is quite shallow, and rushes and Queen of 

 the Meadow and King Cups grow on little marshy mounds with water all 

 round them. These close up, and grasses and sedges and buttercups grow 

 in between, and the land is almost firm and established enough to be 

 called meadowland. Behind the grassy strip creeps down the forest, and 

 the trees, keeping their distance behind the zone of grass, advance with 

 its advancing edge till in time the opposite shores meet and the forest 

 closes over the space once occupied by the pond. When this has hap- 

 pened, we see that the one community of plants, viz., the woodland, has 

 ousted the other, the community of water plants. It is not only indi- 

 viduals that struggle against each other, but whole communities that 

 usurp each other's place. Here, indeed, we can hardly say that there is 

 a struggle between the land and the water plants and those of the shallow 

 shore, because by their natural growth and accumulation the former merely 

 follow on where the latter have, by their own growth, rendered the place 

 no longer suitable for themselves, but well adapted for those which need 

 a built-up soil. 



"Recently it has been recognised that there are definite laws which 

 govern the series of communities that inhabit a region, and a trained 

 ecologist, seeing one set of plants growing under certain conditions, can 

 predict accurately what type of community will follow it always supposing 

 that there is no great physical change, such as would be caused by the 

 sweeping away of the land by a great flood or its disturbance by a landslide. 



'"We have long had various shades of black and crimson and white 

 poppies, but no shade of blue. Out of 200,000 seedlings I found one showing 

 a faintest trace of sky blue and planted the seed from it, and got next year 

 one pretty blue one out of the many thousands, and now I have one almost 

 pure blue.'" (Luther Burbank, as quoted by D. S. Jordan and M. L. Kellogg, 

 Ifie Scientific Aspects of Luther Burbank's Work, 1909, pp. 101-102.) 



