CONTINUITY. 219 



in each longitude with representatives of the mountain flora 

 of the more temperate 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 

 multitude of facts that have been applied in confirmation of 

 the derivative hypothesis. This flora is found to have relation- 

 ships with those of temperate Europe and North Africa, of 

 the Cape of Good Hope, and of the mountains of tropical 

 Madagascar and Abyssinia, such as can be accounted for on 

 no other hypothesis but that there has been ancient climatal 

 connection 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 will become more prehensile, the 

 muscles which act upon those claws must become more de- 

 veloped, 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 effect 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 de- 

 velopment, and the relations shown in what is termed the 

 metamorphosis of plants ; facts difficult to account for on the 

 theory of frequent separate creations, but almost inevitable on 

 that of gradual succession. So also the existence of rudimen- 

 tary and effete organs, which must either be referred to a 

 lusus natures 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 theory ; and, after all, what are these types ? It must be 

 admitted there are none such in reality ; how are we led to the 

 theory of them ? simply by a process of abstraction from 

 classified existences. Having grouped from natural similitudes 

 certain forms into a class, we select attributes common to each 

 member of the class, and call the assemblage of such attri- 



