534 HEKBERT'S THEORY OF SOILS. 



perhaps because of any peculiar food which they find on trees, 

 but because wood is a bad conductor of heat, and because they 

 find shade among branches, while rocks conduct heat more 

 rapidly, and are exposed to more dryness or to more wetness. 

 If rocks are soft, shaded, and so placed as to be exposed to no 

 sudden changes of temperature, then Epiphytes grow as weU 

 on them as on trees. 



Dean Herbert, a most acute anfl experienced gardener, held 



that PLANTS DO NOT GEOW NATUBAILY IN THE SOIL BEST 



SUITED FOR THEM. He Contended that the reason why many 

 plants are found in peculiar places is not at aU because they prefer 

 them, but because they alone are capable of existing there, or 

 because they take refuge there from the inroads of stouter 

 neighbours who would destroy them .: and consequently he by 

 no means advised the gardener to imitate, in a servile spirit, 

 all that he saw happening in the abodes of wild vegetation. 



" I saw,'' said the Dean, " a Crocus, a Sternebergia, and an 

 Ornithogalum growing in contact with each other aloft on the 

 meagre sod of Mount (Enos ; but not a seed-pod of the Sterne- 

 bergia could be discovered, and very few of the Crocus. In a 

 more fertile sod they would have been choked by some stronger 

 plant, but they would rejoice in a better soil, if protected 

 against the oppressor. * * * The compost in which the Dutch 

 raise their improved bulbs of various kinds is known to be (see 

 Sismondi, des Jacinthes) a compost of humus, obtained from 

 thoroughly decayed Elm-leaves and dung of stall-fed cattle, 

 and mixed with sand deposited by the sea on a bed of prostrate 

 timber of unknown antiquity, in which there is probably 

 nothing calcareous. Does it not then appear that the case 

 stands thus — not that calcarieous matter is essential to the 

 growth of Crocus, or even a useful auxiliary, but that Crocus 

 can bear the sterility of elevated calcareous mountains better 

 than most other plants of stronger growth ? If that be true of 

 one genus, it will probably be applicable to others. * * * It 

 will be found that Orchis latifolia, removed from the swamp, 

 in which it struggles with other swamp -plants, will grow more 

 vigorously where it is cultivated with less wet. The small 

 Polygala vulgaris is stated in Mr. Babington's Manual to grow 



