38 



Transactions of the 



[Sess. 



conditions of soil and climate. And when long generations are 

 conceded in order to adapt a plant to its environment, one can 

 easily understand how the change from the normal type might be 

 great indeed. This explanation is, however, at best a partial one, 

 and does not at all account, besides, for resemblances in special 

 organs, as in fruit or flower. Hybridisation has been addiiced as 

 probably a concurrent cause ; but this theory is naturally beset 

 with so many difficulties, that it has not met with much favour. 

 The last resource has been to take refuge in the pre-Darwinian 

 doctrine of Design as an answer to the whole difficulty, and to 

 suppose, with Mr A. W. Bennett, that there is in all this some 

 piu'pose " not in every case for the immediate advantage of the 

 individual species, but in furtherance of some plan of general har- 

 mony which it may take centuries of unwearied and laborious toil 

 before we discover tlie key by wiiich we may be able to unlock it." 

 This idea seems at first blush a very plausible one ; but a little 

 reflection soon shows that it is most unsatisfactory as an explana- 

 tion, for it simply defers any attempt at a solution to a very 

 indefinite period. We cannot expect that the conclusion here 

 arrived at will receive general acceptance ; and it is to be hoped 

 that some other interpretation of the mystery which will meet all 

 the necessities of the case will by-and-by be forthcoming. 



By the kindness of Mr Sadler, Curator, Royal Botanic Garden, 

 Edinburgh, the folloiuing plants were exhibited in illustration of 

 the above paper : — 



Menziesia caerulea, 

 Empetrum nigrum, 



Thujopsis Isetevirens, 

 Selaginella Lyallii, 



Potentilla alchemilloides, 

 Alchemilla alpina, 



Veronica salicomioides, 

 Daci-ydium Franklinii, 



Osmanthus illicifolius, 

 Ilex aquifolius, . 



{Green and variegated forms 



Ciirculigo sumatrana, . 



Cocos flexuosa, .... 



Carludovica palmata, . . . , 

 Livistona chinensis, . . . , 



Ericaceffi. 

 Empetraceffi 



Coniferae. 

 Lycopodiacete. 



Rosacese. 

 Rosaceoe. 



Scrophulariaceee. 

 Coniferte. 



Oleacese. 

 Ilicine33. 



of both shrubs. ) 



Hypoxidacere. 

 Palnife. 



Pandanaceoe. ) 

 Palma3. ( 



