DEVELOPMENT AND STRUCTURE OF THE ANTHER. 247 
The anther in its mature form presents therefore, in nearly 
all cases, but two coats, as shown in figs. 513 and 521, that is, an 
exothecum (fig. 521, ce), or outer coat; and an endothecium, cf, 
or inner coat, which corresponds in structure to the mesothecium 
of the immature anther. The connective, as a general rule, has 
a similar structure to the filament. Each lobe of the anther, as 
already noticed, is divided at an early age into two cavities, by 
the septum (fig. 515), which extends from the connective to the 
suture. This septum, which forms the placentoid of Chatin, is 
usually more or less destroyed when the pollen is matured, but 
generally traces of it may be seen in the form of cellular projec- 
tions from the connective, by which each cell of the anther is 
Lels Ae 
Fre. 520, 
Fiy. 520. Vertical section of 
a loculus or cell of a young 
anther of the Melon. ce. 
Epidermal layer constitut- 
ing the exothecium or 
outer covering of the an- 
ther. ci. The parenchyma- 
tous cells forming the meso- 
thecium. cm, cm. The two 
central masses of cells 
which are placed in each 
half or lobe of the anther, 
in which the pollen is 
formed, and hence they are 
termed parent or mother cells. These cells are surrounded by a special 
layer of cells, cl, forming the endothecium or tapetum. From Le Maout. 
Fig. 521, Horizontal section of a portion of the wall of a mature anther of 
Cobeea scandens at the time of dehiscence. It is composed of an external 
epidermal layer, ce, forming the exothecium, and an internal layer of 
fibrous cells, ef, which is commonly termed the endothecium, and which 
is the mesothecium of the immature anther. 
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mnntey 
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partly subdivided. To these processes the name of placentoids 
was given by M. Chatin, under the impression that they assisted 
in the nourishment of the pollen. 
We have already shown that the floral envelopes are homo- 
logous with leaves, representing them as they do in all their 
essential characters (pages 224 and 230). We have now to ex- 
amine the stamen with the view of ascertaining whether its parts 
have in like manner any resemblance to those of the leaf. We 
have no difticulty in recognising the filament as the homologue 
of the petiole, as in its form, position, and structure it is essen- 
tially the same (page 242). The connective of the anther, again, 
is clearly analogous to the midrib of the blade, and hence we 
