76 THE WORLD OF LIFE 



intendent or keeper would have time and opportunity for the 

 collection of specimens of all the shrubs, climbers, epiphytes, 

 and herbs that grew in the reserve, identifying the place of 

 all the rarer species by direction and distance from the 

 nearest named tree, the epiphytes, orchids, ferns, mosses, etc., 

 being identified by the tree they grew upon being numbered, 

 and made accessible by a path. Of course this area of 3 square 

 kilometres, or about a square mile, may not be in all cases 

 sufficient, but it seems likely to be the most suitable for 

 luxuriant tropical forests. In more open country, as at 

 Campo Santo, a space of from 10 to 50 square miles might 

 be advisable, because the trees on such an area might be as 

 easily found as in a mile of unbroken forest, and would not 

 be much more numerous. In any new tropical country of 

 which we obtain possession, or where there are still large areas 

 of virgin forest, it would be advisable to reserve one square 

 mile in each square degree, say one in every 5000 square 

 miles. 



There are many incidental advantages in this thorough 

 determination of the plants growing on a definite if small 

 area over that which has usually been adopted of, as it were, 

 skimming the cream of the flora of enormous areas, such as 

 most of our botanical collectors have been obliged to adopt. 

 The first advantage is that the census of species in each of 

 the reserved areas can be easily made exhaustive, and there- 

 fore comparable with other similar reserves. Then, when a 

 few well-chosen " reserves " are similarly treated, the change 

 of species in each degree of latitude and longitude can also 

 be determined with considerable accuracy. In like manner 

 the change of species for each I ooo or 5 oo feet of elevation 

 can also be found. Again, the proportion of forest trees to 

 the whole of the flowering plants in each locality will enable 

 the whole flora of a large district to be determined as to 

 numbers by ascertaining the number of species of trees only 

 in a few small areas. 



As an illustration of this mode of computation Dr. 

 Koorders has found that on the Pangerango mountain the 

 trees form one-fifth of the whole flora, while on Kambangan 

 Island they form one-fourth. If there are, as Dr. Koorders 

 tells me, about 1200 species of trees actually found in Java, 



