Metaphyta L iliu m 165 



two lobes becomes the future connective ; the filament is 

 an after- formation. The lobes are covered by epidermis 

 and the layer immediately beneath it divides into two layers, 

 the inner of which becomes the archespormm, whilst the 

 outer layer subdivides into three layers, the inner two of 



FIG. 85. -DEVELOPMENT OF THE STAMEN. 



A, transverse section of young stamen ; B, c, stages in the development of 

 the anther ; u, pollen grain ; E, pollen tube developing from the repro- 

 ductive cell ; a, epidermis ; 3, bundle sheath ; c, fibro-vascular bundle ; 

 J, layer which will become the tapetal layers, d' t d" ; f, vegetative 

 cells ; /J reproductive cell ; g, intin. 



which become disorganised and form tapetal tissue ; the 

 outer becomes, with the epidermis, the wall of the sporan- 

 gium. The cells composing this inner layer have their walls 

 irregularly thickened, and form what is known as the endo- 

 thecium, while the term exothecium is sometimes given to 

 the epidermis. The archesporium forms mother spore-cells, 



