192 
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 
Fig. 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. 
Copyright by 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 
