CHAP. xx. PROGRESSION CONSIDERED. 405 



higher groups in the natural method of classification. He 

 also adds that the earliest recognisable cryptogams are not 

 only the highest now existing, but have more highly diffe 

 rentiated vegetative organs than any subsequently appearing, 

 and that the dicotyledonous embryo and perfect exogenous 

 wood, with the highest specialised tissue known (the coniferous 

 with glandular tissue),, preceded the monocotyledonous em 

 bryo and endogenous wood in date of appearance on the 

 globe facts wholly opposed to the doctrine of progression, 

 and which can only be set aside on the supposition that they 

 are fragmentary evidence of a kind farther removed from the 

 origin of vegetation than from the present day.* 



It would be an easy task to- multiply objections to the 

 theory now under consideration ; but from this I refrain, as I 

 regard it not only as a useful r but rather, in the present state 

 of science, as an indispensable hypothesis, and one which, 

 though destined hereafter to undergo many and great modifi 

 cations, will never be overthrown. 



It may be thought almost paradoxical that writers who are 

 most in favour of transmutation (Mr. C. Darwin and Dr. J. 

 Hooker, for example) are nevertheless among those who are 

 most cautious, and one would say timid, in their mode of es 

 pousing the doctrine of progression ; while, on the other hand, 

 the most zealous advocates of progression are oftener than 

 not very vehement opponents of transmutation. We might 

 have anticipated a contrary leaning on the part of both, for 

 to what does the theory of progression point ? It supposes 

 a gradual elevation in grade of the vertebrate type, in the 

 course of ages, from the most simple ichthyic form to that 

 of the placental mammalia and the coming upon the stage 

 last in the order of time of the most anthropomorphous 

 mammalia, followed by the human race this last thus ap- 



* Flora of Australia, Introductory Essay, p. xxi. London, 1859. Published 

 separately. 



