108 The Ilev. P. Kcilh on the Classificativn of Vci;ctuhlc$. 



ll 



llcncc 11"=^.' 



,= -X.x 



t 



Conipouiulin^^ now tlie four Inices f, p\ R', K", llie first two 

 destroy each other, llie hitler two give a siun ; that is, 



11 = R' H- R" = ,; or R« = X^ + Y^ 



Y 



Having proved tliat ^ = tan (3) and IV = X" + Y^ we 



easily obtain X = Rcosfl, Y = 11 sin 6, wliich contain the 

 j)rincipies of the composition and decomposition of any forces 

 acting on a plane npon one point. 

 2, Bate;nan's Buililings, Soho, Dec. 23, 1836. 



XXIV. On the Classification of Vegetables, 

 By the Rev. Patrick Kkith, 1\L,S, 

 [Continued from p. 42, and concluded.] 



ZITHERS have innovated upon Jussieu's nomenclature and 

 ^^general plan of arrangement, but it may be doubted whe- 

 ther they have in this respect improved the system. We will 

 specify only two examples. 



I. M. DeCandolle, Professor of Botany at Geneva, an 

 acute and skilful systematist, exhibits the first examplt of in- 

 novation. In his Theorie Elemeutaire and ProdromiiSy he 

 substitutes the term Exogenas in place of Dicotyledons, and 

 the term Endogenic in the place of Monocotyledons and Aco- 

 tyledons; but we can see no advantage that is gained by the 

 substitution. MM. Desfontainesand Daubenton had already 

 shown that Dicotyledonous plants are exogenous, and Mono- 

 cotyledonous plants endogenous, and Jussieu was well enough 

 aware of the fact. The new terms, we admit, were not yet 

 imposed ; but if exogenous and endogenous are respectively 

 identical in their extent, with Dicotyledonous plants on the one 

 hand and with Monocotyledonous plants on the other, whence 

 could the advantage of the substitution come? And if you ex- 

 tend the meaning of endogenous so as to make it include Aco- 

 tyledonous plants also, we (juestion the legitimacy of the ex- 

 tension, and contend that their endogeneity is not at all of the 

 same character with that of the Monocotyledons. Besides, 

 the change of term.** leaves the affair of method precisely where 

 it was, while it has the effect of keeping Jussieu and his di- 



