OP HOT A NY XXVII 



ili.'j. Tliey consist of a bundle of spiral vessels surrounded by cellular tissue, 

 • ailed the filament, terminated by a peculiar arrangement of the cellular tissue in a 

 case, finally opening and discharging its contents, called the anther. 



304. There are many instances in which no limits can be traced between the 

 petals and stamens ; Ex. Nymphaea. 



305. In such cases it is found that the limb (295) of the petal contracts and be- 

 comes an anther, while the unguis assumes the state of a filament. 



306. Now as there are no limits between the petals and sepals (282), nor between 

 the sepals and bracteae (278), nor between the bracteae and leaves (229), it follows 

 that the stamens are also a modification of leaves. 



807. And as the limb of a petal is analogous to the lamina, and the unguis (295) 

 to the petiole of a leaf, it also follows that the anther is a modification of the lamina, 

 and the filament of the petiole. 



308. The stamens follow the same laws of successive developement as leaves ; 

 and consequently, if their arrangement be normal, they will be either equal in num- 

 ber to the petals, and alternate with them, or, if more numerous, some regular mul- 

 tiple of the petals. 



309. If they are twice the number of petals, two whorls arc considered to be de- 

 veloped ; and so on. 



310. If they are equal in number to the petals, and opposite them, it is to be un- 

 derstood that the innermost only of the two whorls is developed, the outermost being 

 abortive. 



311. All deviations from these laws are due to the abortion of some part of the 

 stamens; Ex. Lamium, Hippuris. 



312. When the stamens do not contract any union with the sides of the calyx, 

 they are hypogynous ; Ex. Ranunculus. 



313. When they contract adhesion with the sides of the calyx, they become pe- 

 rigynous ; Ex. Rose. 



314. If they are united both with the surface of the calyx and of the ovarium, 

 they are epigynous ; Ex. Umbellifera?. 



315. The filaments (303) are either distinct or united by their margins. If they 

 are united in one tube, they are called monadelphous ; Ex. Malva: if in two par- 

 cels, diadelphous ; Ex. Pea : if in several, polyadelphous ; Ex. Hypericum. 



316. When they are united in a solid body, along with the style, they form what 

 is called a column, and are said to be gynandrous. 



317. The filament is not essential to a stamen, and is, in fact, often absent. 



318. The anther is the limb of the stamen, forming within its substance, and 

 finally emitting, a matter called pollen. 



319. The two sides of the anther are called its lobes ; and the solid substance 

 which connects them, and which is in fact a continuation of the filament, as the mid- 

 rib of a leaf is of the petiole, is named the connectivum. 



320. The cavities of the anther containing the pollen are the cells, and the 

 place by which the pollen is emitted is the point or line of dehiscence ; the mem- 

 branous sides of the anther are named the valves. 



321. Dehiscence usually takes place along a line, which may be considered to 

 indicate the margin of the limb out of which the anther is formed ; Ex. Rose. 



322. Sometimes a portion only of this line opens, and then the anther is said to 

 dehisce by pores ; Ex. Azalea. 



323. If the line of dehiscence occupies both margins of the connectivum, and not 

 1he centre of the lobes, the anther opens by one valve instead of two, which is then 

 hinged by its upper edge ; Ex. Berberry. 



324. The cells of the anther are usually two in number : sometimes they are 

 four ; Ex. Tetratheca : rarely one ; Ex. Epacris : and still more rarely several ; 

 Ex. Raffiesia. 



325. The number of cells appears to be determined by no certain rule. 



326. The anthers frequently grow together by their margins ; Ex. Composites. 

 Such anthers are called syngenesious. 



327. The Pollen is formed by a peculiar modification of the cellules of the paren- 

 chyma of the anther. 



328. That part of the central cellular tissue of the anther which is not converted 

 into pollen, serves to connect the granules together, in the form of a tenacious 

 -fibrous web ; Ex. Oenothera, Orchis. 



