200 Comparative Physiology. 



of knowledge names are alike necessary. For the acquirement 

 of names, especially in small local floras, the Linnaean was the 

 most easy ; many of the classes were natural, and some forcible 

 separations from them, by abortive stamens, &c., were remedied, 

 in some works, by references at the stations to which alterations, 

 &c., would lead. To gardeners, and other students in the 

 country, where botanical named collections cannot be referred 

 to, the Linn£ean system is most simple, and the distinctions most 

 easily remembered. The most popular works were also based 

 on that system, and in such as the Botanical Arrangements of 

 Withering, Smith, Hooker, &c., so much attention has been 

 paid to individual plants, from their number being more limited 

 in local floras, and the facility of reference to plants growing in 

 a state of nature, that the distinctions were very marked, and 

 the plants comparatively more easily decided on. In the natural 

 systems a greater mass of characters are grouped together, and 

 it is more easy to combine them synthetically ; but the arriving 

 at the name is an analytical process, and it is more labour for 

 the student to select distinguishing characters among so many 

 as are generally given in natural systems. To the student in the 

 country, who has not the benefit of a preceptor, nor of a named 

 collection, the natural systems are likely, therefore, to appear, at 

 least at first, more repulsive. 



The deficiencies in the Linnaean system, however, have be- 

 come more apparent, from the immense additions lately made to 

 the number of plants. In small local floras these defects were much 

 remedied by references ; but the separation of natural groups re- 

 quired to follow it up completely, in the general flora, were many, 

 and hence natural systems are now most generally approved of. 

 They combine plants more according to their natural affinities ; 

 which, though found to anastomose together in the extremities, 

 are yet, for practical purposes, sufficiently distinctive to enable 

 the mind to comprehend and arrange them in groups, which 

 assist the memory to retain a comprehensive idea of the whole, 

 and refer them to their stations more easily than under artificial 

 characters. When orders, alliances, and groups are properly 

 based on real, not analogous, affinities, by a strict conformity in 

 the essential parts of fructification, as in the grasses, composite 

 flowers, Labiatfe, Cruciferte, &c., it greatly facilitates the com- 

 prehensive idea of the whole in parts. Even genera, as J?6sa, 

 i?ubus, &c., often admit of distinctive natural affinities. Most 

 of the divisions are, however, still artificial, and natural systems 

 are still very imperfect; sufficient attention has not yet been 

 paid to the drawing out of the distinctions of plants, in perma- 

 nent structural diflerences. In works of descriptive botany, one 

 single such character is of infinitely more value than an immense 

 mass of others, which only tend to confusion. Much has been 



