ADDRESS. IXXV 



Selection,' at the same time declining the doctrine of special creation, has 

 since then cordially adopted the former, and illustrated its principles by 

 applying them to the solution of various botanical questions : first, in refer- 

 ence to the flora of Australia, the anomalies of which he appears to explain 

 satisfactorily by the application of these principles ; and, latterly, in reference 

 to the Arctic flora. 



In the case of the Arctic flora, he believes that originally Scandinavian 

 types were spread over the high northern latitudes, that these were driven 

 southwards during the glacial period, when many of them changed their 

 forms in the struggle that ensued with the displaced temperate plants ; that 

 on the returning warmth, the Scandinavian plants, whether changed or not, 

 were driven again northwards and up to the mountains of the temperate 

 latitudes, followed, in both cases, by series of preexisting plants of the tem- 

 perate Alps. The result is the present mixed Arctic flora, consisting of a 

 basis of more or less changed and unchanged Scandinavian plants, associated 

 in each longitude with representatives of the mountain flora of the more tem- 

 perate regions to the south of them. 



The publication of a previously totally unknown flora, that of the Alps of 

 tropical Africa, by Dr. Hooker, has afforded a miiltitude of facts that have 

 been applied in confirmation of the derivative hypothesis. This flora is found 

 to have relationships with those of temperate Eui'ope and North Africa, of 

 the Cape of Good Hope, and of the moimtains of tropical Madagascar and 

 Abyssinia, that can be accounted for on no other hypothesis, but that there 

 has been ancient climatal connexion and some coincident or subsequent slight 

 changes of specific character. 



The doctrine of Cuvier, every day more and more borne out by observation, 

 that each organ bears a definite relation to the whole of the individual, seems 

 to support the view of indefinite variation. If an animal seeks its food or 

 safety by climbing trees, its claws wiU become more prehensile, the muscles 

 which act upon those claws must become more developed, the body will become 

 agile by the very exercise which is necessary to it, and each portion of the 

 frame will mould itself to the wants of the animal by the eflTect on it of the 

 habits of the animal. 



Another series of facts which present an argument in favour of gradual 

 succession, are the phases of resemblance to inferior orders which the embryo 

 passes through in its development, and the relations shown in what is termedthc 

 metamorphosis of plants ; facts difiicult to account for on the theory of fre- 

 quent separate creations, but almost inevitable on that of gradual succession. 

 So also, the existence of rudimentary and eff'ete organs, which must either be 

 referred to a Jusiis naturce or to some mode of continuous succession. 



The doctrine of typical nuclei seems only a mode of evading the difficulty ; 

 experience does not give us the types of theoiy, and, after all, what are these 

 types ? It must be admitted there are none such in reality ; how are we led 

 to the theorj' of them ? simply by a process of abstraction from classified exist- 

 ences. Having grouped from natural similitudes certain forms into a class, 

 we select attiibutes common to each member of the class, and call the assem- 

 blage of such attributes a type of the class. This process gives us an abstract 

 idea, and we then transfer this idea to the Creator, and make Him start with 

 that which our own imperfect generalization has derived. It seems to me 

 that the doctrine of types is, in fact, a concession to the theory of continuity 

 or indefinite variability ; for the admission that large groups have common 

 chai'acters shows, necessarily, a blending of forms within the scope of the 

 group, which supports the view of each member being deriyed from some 



