THE JUSSIEUAN SYSTEM. 185 



affinities, that it has been found indispensable to have recourse to 

 certain arbitrary or artificial characters for the foundation of the 

 sections characters derived chiefly from the conditions of the 

 petals and stamens. The nature of these Sections will be best un- 

 derstood from the examples which follow. 



The Jussieuan System. Jussieu established his primary divi- 

 sions of the Vegetable Kingdom on characters which, although not 

 unexceptionable, define really natural groups, which are found 

 under different titles in all Natural Systems. The characters 

 were the absence or presence of the embryo, and its structure when 

 present, in the seed. On these characters stood the three divisions 

 Acotyledons (plants without an embryo), Monocotyledons, and Dico- 

 tyledons. The first of these names is bad, as founded upon a nega- 

 tive character ; but the plants which it included were imperfectly 

 understood in the time oi: Jussieu ; the Acotyledons correspond to 

 the Cryptogamia of Linnaeus, which are now by more complete 

 analysis distributed into two sections, divided by even more im- 

 portant characters than the Monocotyledons and Dicotyledons. 

 The other two divisions are still retained, with very slight modifi- 

 cations, in all Systems, but are subordinated under divisions founded 

 on more important characters. 



The following Table exhibits Jussieu's arrangement : 



Class 



Acotyledons ............................................ 1. 



Stamens hypogynous ........ II. 



perigynous ........ III. 



epigynous '. ......... IV. 



Stamens epigynous .......... V. 



perigynous ........ VI. 



hypogynous ..... '. . . VII. 



( Corolla hypogyuous ........ VIII. 



perigynous .......... IX. 



MONOPETALOUS ( Anthers I 



Monocotyledons 



f APETALOUS 



Dicotyledons .] I epigynous 



( distinct ( 



{Stamens epigynous .......... XII. 

 hypogynous ........ XIII. 

 perigynous ........ XIV. 



I DICLINOUS, irregular ........................ XV. 



The three primary divisions here are natural ; the Classes must be re- 

 garded as artificial ; the Families, however, into which the latter are 

 divided, are natural groups, and to a great extent are retained in more 

 modern systems. The families of Jussieu were more carefully defined, 

 corrected, and extended by liooert Brown, whose researches contributed 

 most essentially to the establishment of the Natural System ; but he did 

 not attempt to establish any general plan for their coordination in Classes. 



