TEMPEEATE FLOIUVS 29 



Here we see that 10 square miles coutaiiied nearly as many 

 species as 60, and nearly two-thirds the nmiibcr in TOO square 

 miles ; while the single square mile produced nearly half the 

 number in the whole county. 



Taking still smaller areas, Mr. Woodruffe-Peacock found 

 fields in Lincolnshire and Leicestershire, of from 10 to 25 

 acres, to yield from 50 to 60 species of plants ; while a plot 

 of 16 Vo feet square (or 1 perch) would usually have 20 to .')0 

 species. Old and long-disused stone-quarries are often very 

 rich, one of about two acres producing sometimes as many 

 species as the fields of eight or ten times the area. On a plot 

 of turf 3 feet by 4, at Down in Kent, Mr. Danvin found 20 

 species of flowering plants growing. 



These facts of the distribution of plants in our own is- 

 lands prove, that for moderately large areas in the same 

 country possessing considerable diversity of soil and general 

 conditions affecting plant-life, the majority of the species are, 

 as a rule, so widely scattered over it that approximately similar 

 areas produce a nearly equal number of species. Further, 

 we find that areas of successively smaller and smaller sizes have 

 a very much greater number of species relatively than larger 

 ones ; so that, as we have seen, 10 square miles may show al- 

 most as much variety in its plant-life as an adjacent area 

 of 60 square miles, and that a single square mile may some- 

 times contain half the number of species foimd in 700 square 

 miles. 



This characteristic of many small areas being often much 

 richer in proportion to area than larger ones of which they 

 form a part, is a necessary result of the great differences in 

 the areas occupied by the several species and the numbers 

 of the individuals of each ; from those very common ones which 

 occur abundantly over the whole country, to others which, al- 

 though widespread, are thinly scattered in favourable situa- 

 tions, down to those exceptional rarities which occur in a very 

 few spots or in very small numbers. Those spots or small 

 areas which present the most favourable conditions for plant- 



