182 LyelVs Principles of Geology. 



That there might be a predominance of tree ferns is pro- 

 bable, but why of plants allied to palms and arborescent 

 grasses p. 153 ? Are palms most common in insular climates ? 

 It is curious also, that if arborescent grasses are so, that 

 there is a want of correspondence between circumstances 

 now existing, and those of the coal formation period, in 

 which no glumaceous plant has been discovered. Yet such 

 plants from the silex they contain, from their abundance, 

 and from their frequently gregarious habits, might be sup- 

 posed to present great facilities to becoming fossilized.* 



2nd. — On the Theory of Progressive Development. 



If Lamarck's theory be true, we require only one — abso- 

 lutely only one original type, because of the gradation be- 

 tween animals and plants, and of certain beings not being 

 apparently referable more to one class than to the other. 



But as in this case, unless the original formative particle 

 branched off dichotomously into two, of which the one was 

 destined to be the stock of all existing animals, the other of 

 all existing plants, he would have to allow the formation of 

 the most imperfect animal from the most perfect plant, 

 and thus follow a retrograde course, a condition obviously 

 fatal to a theory of progressive development. But similar 

 instances of a retrograde course may be proved to exist in 

 many parts of the series of animated nature. We have some 

 plants with highly developed organs of vegetation, and little 

 developed sexual organs ; (Mosses and Ferns,) and others 

 again presenting precisely opposite circumstances, allied ne- 

 vertheless to the former. Now this obviously includes a 

 retrogression in the vegetative organs of the latter. Again, 

 Lamarck admits several points of formation : he admits even 

 distinct points for the principal families : this is a fatal admis- 

 sion. To a supreme cause, the increase in the number of 



* Consult Brongniart's Sur la Nature de la Veget. Annales des Sciences, 

 November, 1828. 



