ESSENTIAL ORGANS. STAMENS. 193 



401. In the case of certain Achlamydeous (^[ 351) flowers, as 

 Euphorbia, with only one stamen developed, there is the appearance 

 of a jointed filament bearing one anther. This, however, is not a true 

 filament, but a peduncle with a single stamen attached to it, as proved 

 by the fact, that in some species of Euphorbia one or more verticils are 

 produced at the joint. Thus the so-called anther is in reality a single 

 flower supported on a stalk, all the parts being abortive, except a 

 solitary stamen. 



402. The Amber corresponds to the blade of the leaf, and consists 

 of lobes or cavities containing minute powdery matter, called pollen, 

 Avhich, when mature, is discharged by a fissure or opening of some 

 sort. The anther-lobes may be considered as formed by the two halves 

 of the lamina, their back corresponding to the under surface, and their 

 face to the upper surface, united by the midrib, the pollen being cellular 

 tissue, and the fissure of the anther taking place at the margin, which, 

 however, is often turned towards the face. In this view, the two 

 cavities which are found to exist in each lobe, may correspond with 

 the upper and under layer of cells, separated by a septum equivalent 

 to the fibro-vascular layer of the leaf. Others view the anther as 

 formed by each half of the lamina being folded upon itself, so that the 

 outer surface of both face and back corresponds to the lower side of 

 the leaf, and the septum dividing each cavity into two is formed by 

 the upper surfaces of the folded half united. 



403. There is a double covering of the anther the outer, or exo- 

 thecium (i%-a, outwards, and 6-tix.iov, a covering), resembles the epider- 

 mis, and often presents stomata and projections of different kinds (fig. 

 318 c e); the inner, or endothecium (s^ov, 



within), is formed by a layer or layers of 

 fibro-cellular tissue (fig. 318 c /), the cells 

 of which have a spiral (fig. 23), annular (fig. 

 24), or reticulated (fig. 25) fibre in their in- 

 terior. This internal lining varies in thick- 

 ness, generally becoming thinner towards the 



part where the anther opens, and there disappears entirely. The 

 membrane of the cells is frequently absorbed, so that when the anther 

 attains maturity the fibres are alone left, and these by their elasticity 

 assist in discharging the pollen. 



404. The anther is developed before the filament, and is always 

 sessile in the first instance. It appears in the form of a small cellular 

 projection, containing a mass of mucilaginous CPUS (fig. 319). In the 

 progress of growth, certain grooves and markings appear on its sur- 

 face, and its interior becomes hollowed out into two marked cavities, 



Fig. 318. Transverse section of a portion of the covering of the anther of Cotea scandens at 

 the period of dehiscence. c e, Exothecium, or external layer, consisting of epidermal cells, c/, 

 Endothecium, or inner layer, composed of spiral cells or inenchyma. 



O 



