382 X. GENERAL REMARKS. 



truth, to show that areas and floras have a numerical 

 decrease at a very unequal rate. The decrease is very 

 much slower for the species than for the spaces. Hence 

 it follows, that the smaller is the area examined, the 

 larger relatively is the flora found upon it. But other 

 conditions modify this general rule in its special applica- 

 tions. For instance, in glancing down the column for 

 numher of species, it is quite evident that they have a 

 decrease in the direction from south to north. The two 

 rates and directions of decrease will interfere with and 

 modify one another ; the result being a less decrease 

 where the smaller area is a more southerly one, and a 

 greater decrease where it is a more northerly area. 



As a more special instance, let the number of miles to 

 a species, or the number of species to ten miles, in the 

 province of East Highlands, be compared with the corre- 

 s^Donding numbers for its three sub-provinces. The rela- 

 tive proportions or numbers are found to be widely 

 different for the whole province and for its three por- 

 tions ; while these third parts of the whole (or there- 

 abouts) agree rather closely with each other. North 

 Wales, whether designated province or subprovince, will 

 admit of comparison with the subprovinces of the East 

 Highlands, on account of its approximate equality of 

 area ; while a comparison of North Wales and East 

 Highlands, as two provinces, would be unsound on ac- 

 count of the latter being thrice the size of the former. 

 Nevertheless, this smaller province of North Wales has a 

 more numerous flora (absolutely, not relatively only) 

 owing to its more southern position, perhaps combined 

 with some other conditions. 



So, again, on looking to the * averages ' for the pro- 

 vinces and subprovinces, as given in the table, it may be 

 observed that one apparent exception is shown to the 



