150 Development of the Natural System under 



endeavour, for the principles themselves which he laid down 

 are not only to a great extent incorrect, but they are opposed 

 to his own and to every other natural system. We find this 

 opposition between theory and practice much more strongly 

 marked in Lindley than in De Candolle ; the cases only are so 

 far different, that De Candolle laid down correct principles for 

 the determination of affinities, but in some cases did not follow 

 them, whereas Lindley deduced quite incorrect rules of system 

 from existing and long-established natural affinities. The con- 

 sideration of all the systems framed up to the year 1853 shows 

 clearly that the characters of truly natural groups are to be 

 found only in morphological marks; yet Lindley enunciates 

 the principle that a mark, or, as he incorrectly says, an organ, 

 is more important for classification in proportion as it pos- 

 sesses a higher physiological value for the preservation and 

 propagation of the individual. If this were true, nothing would 

 be easier than to frame a natural system of plants ; it would 

 suffice to divide plants first of all into those without and those 

 with chlorophyll, for the presence of chlorophyll is more essen- 

 tial than that of any other substance to the nourishment of 

 plants, and its physiological importance is therefore pre- 

 eminent ; in that case of course such Orchideae as have 

 no chlorophyll, the Orobancheae, Cuscuta, Rafflesia, etc., 

 would form one class with the Fungi, and all other plants the 

 other. It is very important for the existence of a plant whether 

 its organisation is adapted to its growing in water, or on dry 

 land, or underground, and if we took Lindley at his word, he 



work contains a somewhat diffuse account of P. de Candolle's doctrine of 

 symmetry, together with Goethe's theory of metamorphosis and Schimper's 

 doctrine of phyllotaxis, and his own views also on classification founded on 

 the comparative morphology of the day. It is marked by fewer errors 

 than will be found in Lindley's theoretical writings, but it is less profound, 

 and touches only incidentally on fundamental questions; at the same time it 

 possesses historical interest as giving a lucid description of the state of 

 morphology before 1840. 



