I Q2 PHARMACEUTICAL BOTANY 



absorbed, thus becoming a one-celled anther with transverse dehis- 

 cence. in its mature state. 



Development of the Anther. Each stamen originates as a knob- 

 like swelling from the receptacle between the petals and carpels. 

 This swelling represents mainly future soral (anther) tissue. The 

 filament develops later. When such a young sorus or anther is cut 



PIG. 95. Cross-section of a mature lily anther. The pairs of pollen chambers 

 unite to form two pollen sacs, filled with pollen grains; s, modified epidermal cells 

 at line of splitting. (From a Text-book of Botany by Coulter, Barnes, and Cowles. 

 Copyrightjoy the American Book Company, Publishers.) 



across and examined microscopically, it shows a mass of nearly simi- 

 lar cellular tissue in which the first observable changes are the 

 following: 



The surface dermatogen cells become somewhat flattened and regu- 

 lar to form the future epidermis or exothecium of the anther. About 

 the same time some cells, by more rapid division in the middle 

 of the anther substance, give rise to the elements of the vascular 

 bundle in the connective. Then, along four longitudinal tracts, 

 rows of cells remain undivided or only divide slowly as they increase 

 in size and around them cells divide and redivide to form the future 

 endothecial and covering tissue to the four sporangia. Next, the 

 four sporangial tracts of undivided cells cut off from their outer 

 surfaces a layer of enveloping^ cells, the tapetum. This consists of 

 richly protoplasmic cells that form a covering to the spore mother-cells 



