THEOEETICAL STRUCTURE. 41 



61. The OVULES are certain little globular bodies, produced in 

 the cells of the ovary, destined to become the seeds in the 

 matured fruit. (Fig. 10; 1.) 



82. The PLACENTA is that part of the ovary from wliich the 

 o\ailes arise, and to which they are attached. It consists of a 

 line, or fleshy ridge, placed in some angle of the cell. Its direc- 

 tion is always vertical, that is, parallel with the axis of gi'owth. 

 (Fig. 10; 1, c/.) 



83. PItysiological structure. The ovary and style are com- 

 posed chiefly of one or more bundles of vascular tissue, imbed- 

 ded in ceflular tissue. Tlie stigma consists of a loose cellular 

 substance, called the conducting tissue, communicating \vith the 

 placenta tln-ough the centre of the style. It is the only ])art of 

 the ascending axis which is destitute of the epidermis (35). 



84. Theoretical structure. The pistil, as before stated (25, a), is the modifica- 

 tion of a leaf, or of a whorl of leaves, each leaf constituting: a cai7jel. Each 

 carpel has its own style and stigma, and is foiTQed of a leaf folded together in 

 such a way that the upper surface becomes the inner, and is turned towards tho 



The 15th cinss, Tetradj-namia, is divided into two orders, which are distinguished 

 by the form of the pod : — 



1. Siliculosa, the frait a silicle, or short pod. 



2. Siliquosa, fruit a silique, or more or less elongated jKxi. 



The orders of the 16th, 17th, ISth, 20th, 21st, and 22<:l classes ai-e of the same 

 name and character as tlie first 13 classes themselves, that is, they are founded 

 upon the number of the stamens to tlie flower, tlms : — 



Order 1, Monandria, includes all Monadelphous plants, Diadclphoxis plants, &c. 

 with one stamen to each flower. 

 2, Diandria, with two stamens to each flower, and so on. 

 The orders of the 19th class, Syngenesia, are five: — 

 Order 1. Equalis (equal), with the florets (flowers) of the head all perfect. 



2. Superflua (superfluous), florets of the i-ays, or margin of the head pistil- 



late, the rest perfect. 



3. Frustranca (frusti-ated), florets of the margin neutral, the rest perfect. 



4. Necessaria (necessary), florets of the margin pistillate ajid fertile, the rest 



staminate and sterile. 



5. Segrcgata (separated), each floret having its own proper calyx. 



Tlie orders of class 23d, Polygamia, are two, founded upon the same ch.iracters 

 as the two preceding classes : — 



1. Monwcia, where both separated and perfect flowers are found in the samo 



individual. 



2. Diwcia, where the diiTerent flowers occupy different individuals. 



The orders of class 24th, Crj-ptogamia, are nine, the same as tlie natural orders 

 of this gi-and division, as FiJices, the fems, Musci, the mosses, &:c 

 4* 



