124 



ous equations containing many unknown quantities, x, y, z, . . . . Different 

 phases of the natural system viewed from different standpoints are to be 

 likened to different equations showing the different relations of the unknown 

 qualities ; and the natural relations wliich we are struggling to demonstrate in 

 constructing a natural system are somewhat similar to the values of the un- 

 known quantities Avhich satisfy the equations. Tin's metaphor, I think, makes 

 sufficiently clear that a natural system should be a dynamic one. 



The characters which ENGLER refers to in Ifi, 17, 18, and 19 l) , as those 

 denoting the stages of advancement, are all the respective peculiarities of the 

 plants and they should certainly be taken into account. 



In 20 2) he states that the whorl arrangement of floral elements usually 

 occurs in con-elation with the inferior ovary or zygomorphy. It is true that 

 the more the characters come in linkage, the less dynamic becomes the 

 system, which shows the natural relations of the plants compared. Conss- 



in the Centrospermre ; Melastomacerc in the Myrtiiior.T? ; Li-n^ibulariaceoj !in<l others in the Tnbi- 

 florre ; and Plantaginacese in the Plantaginales. 



SECRETORY CELLS, OF VABIOOS SHAPE-;. WITH RESINOUS (OILY). LATEX-LIKE OR OTHER CONTENTS, 

 are found in the following families respectively : Caly>-anthac2:B an 1 others in the Ramies ; 

 Papaveracese and others in the Bhoeadales ; Bixacerc in the Parietales ; Polygalaeerc and others 

 in the Geraniales ; Sapindaceae and others in the Sapindales ; Legumin ).s;e and others in the 

 Eosales ; Myrtacerc and others in the Myrtiflorns ; Cornacere in the Umbelliflorfe ; Rubiacesa 

 and others in the Rubiales ; Compositie and others in the Campanulatre ; Plumbaginacere in the 

 Plnmbaginales ; Primulacere and others in the Primulales ; Apooynacere and others in the 

 Contortas ; Convolvulacere and others in the Tubiflorre ; Aristolochiaoere in the Aristoloehiales ; 

 Piperacere and others in the Piperales ; Myristieacese and others in the Ranales ; Euphorbiacere 

 and others in the Geraniales ; and Moraceoe in the Urticales. 



ELONGATED SECRETORY SACS are found in the Trochodendracene and others in the Ramies ; 

 Anacardiaoese in the Sapindales ; Crassulacene and others in the Eosales ; Passifloraceae in the 

 Parietales ; Rubiaceaa and others in the Rubiales ; Composite and others in the Campanulate ; 

 Polygonacere in the Polygonales ; Myristicacere in the Ranales ; and Eiiphorbiacere in the Geraniales. 



TANNIN IDIOBLASTS are foitnd in the Violace;e and others in the Parietales ; Geraniaceaj in the 

 Geraniales ; Rhaninacerc and others in the Ehamnales ; Legumin os;e in the Rosales ; Melastomacere ; 

 in the Myrtiflorte ; Rubisicere in the Rubiales ; Pirolacere in the Eficales ; Gentinnaceie in the 

 Contortfe ; Solanacere and others in the Tubiflorre ; Polygonaeeaj in the Polygonales ; Aristolo- 

 chiacea; in the Aristoloehiales ; Piperaeeoi in the Piperales ; Euphorbiac:e;e in the Geraniales ', 

 Moracerc in the Urticales ; and Ceratophyllacere in the Panales. 



INTRAXYLARY PHLOEM is found in the following families : VochysLoceai in Geraniales ; Combretacene, 

 Myrtacens, Melastomataceie and others in the Myrtiflome ; Cucurbitacena in the Cucurbitales ; Apocy- 

 naceaj and others in the Contortie ; Convolvulaceae and others in the Tubirlorie ; Basellacere in 

 the Centrospermre ; Polygonacea? in the Polygonales ; and Eiiphorbiacens in the Geraniales. 



1) ENGLER, A. 1. c. pp. XIV. XV. 2) ENGLER, A. - 1. c. p. XV. 



