iv TROPICAL FLORAS 81 



the botanist can often collect more species in the same time, 

 because diversities of soil and station are more crowded 

 together, but the accurate determination of the species on 

 areas from one square mile up to some hundreds of miles 

 shows that the fact is almost uniformly the other way. 



It is also of special interest to note that the well-known 

 fact in our own country, that a parish of 2 or 3 square 

 miles in area often contains more than half the flora of the 

 whole county many hundred times as great (as in the cases 

 of Cadney, Edmondsham, and Thames Ditton, given in the 

 table), appears to be even exaggerated in the more luxuriant 

 tropical forests, where a single square mile often contains as 

 many species as 100 miles in similar forests elsewhere. 



It is, however, interesting to note that when we compare 

 very small areas, measured by feet or yards instead of by 

 square miles, it is the temperate floras which seem to have 

 a decided advantage. Darwin records that on a piece 

 of turf 3 feet X 4 feet, long exposed to uniform conditions 

 (probably on the chalk downs of Kent or the Isle of Wight), 

 he found twenty species of plants belonging to eighteen 

 genera (Origin of Species, 6th ed. p. 88). Sir Joseph 

 Hooker in the Himalayas, 11,480 feet above the sea, in the 

 upper Lachen valley, found a much richer vegetation. He 

 says : " Herbaceous plants are much more numerous here 

 than in any other part of Sikhim ; and sitting at my tent 

 door I could, without rising from the ground, gather forty- 

 three plants, of which all but two belonged to English 

 genera." And in a note he adds : " In England thirty is 

 on the average the equivalent number of plants which in 

 favourable localities I have gathered in an equal area." l 



In my limited reading I have found no other reference 

 to this form of species-abundance, nor do any of my 

 botanical friends appear to have recorded such ; but it 

 would be interesting to know if any parts of Switzerland or 

 the Pyrenees are as rich as the Himalayas. I should 

 expect not, as the latter has a great advantage in area, 

 and also I presume in climate. The snow protection in 

 winter would be similar, but I presume the summer would 

 be somewhat longer and the temperature more equable, 

 1 Himalayan Journals (cheap ed.), p. 335. 



G 



