INTRODUCTION 51 



numerous stamens, they are distinguished by the 

 different position of the stamens in the latter group. 



A more general and common character (or char- 

 acters) is employed to arrange such orders into classes. 

 Thus, whilst in Ranunculacese and Alismacese the 

 stamens are inserted upon the receptacle, the former 

 includes species in which the embryo is provided 

 with two cotyledons, and therefore the plants are 

 Dicotyledons, whereas in the latter there is but one 

 which sheaths the plumule at first, and the order is 

 monocotyledonous. In the Ranunculaceae it is true 

 there are several species which have but one cotyledon, 

 as in R. Ficaria, this being a character connected by 

 some with an adaptation to aquatic conditions. But 

 a further distinction between the two classes lies in 

 the number of the parts of the flower, five or four in 

 the former, three or a multiple of three in the latter."^ 



Classes may be divided up into sub-classes. So also 

 by the prefix of the same syllable minor divisions 

 may be made of other groupings. The class Dicoty- 

 ledons is sub-divided thus into four sub-classes by 

 Bentham and Hooker, into two by Engler and Prantl. 

 In the former case we have Thalamiflorae, Calyciflorse, 

 Gamopetalae, and Apetalae. The characters of these 

 sub-classes are given in the descriptive part of the 

 Introductory Volume and the two other volumes. 



The classes are grouped together as phyla, lines of 

 descent or tribes, and of the two phyla the flowering 



* This double distinction apart from others, as the Venation, serves 

 to show the classification is more or less natural. 



