1892.) Botany. 1033 
Turning now to the order of development of flower parts, the first 
foliar structure that appears is a petal. At first they appear as small 
papillae on the annular wall. In their further development the tissue 
thickens and the epidermal cells with their rather heavy cell walls 
become quite large; in later growth their tissue becomes more uniform, 
and the tips of the five marginal teeth of the corolla-tube turn inward, 
thus furnishing an excellent protection to the andrecium and gyne- 
cium. The petals forming the flower tube are not simply contiguous 
but united, and as the tube elongates it assumes, slightly, the form of 
a funnel whose upper margin has five spreading teeth. The tubular 
corolla is not composed of parts originally separate and subsequently 
united by their lateral margins, for the parts set free are the marginal 
teeth arising from a common basal tissue; and this tissue develops and 
elongates pari passu with the growth of the nascent organs within. 
Almost immediately following the visible corolla, appearing on its 
inner basal margin, are five minute elevations, the rudimentary sta- 
mens. These develop with remarkable rapidity, and their primitive, 
oval form is soon exchanged for one that is oblong. The histological 
- constituent of the stamen in its early growth isa mass of uniform 
parenchyma. Presently a new condition arises; a differentiation of 
tissue into anther lobes and a connective takes place. The fibro-vas- 
cular bundle, which is a continuation of that of the flower-axis, 
though very much reduced, differentiates in the upper part of the 
stamen, and forms the so-called connective. At the same time there is 
a modification of tissue which develops into anther lobes; these are 
connected and yet separated by the connective. In the early process 
of growth there appear two longitudinal ridges on each half-anther 
lobe; these answer to the future pollen sacs, and give rise to the arch- 
esporium cells, which, usually having but one row in each pollen-sac, 
again give rise to the squarish mother-cells; in turn the latter yield 
four pollen grains each. The developmental path, pursued by all 
pollen grains, is so common that space is of more avail than their fur- 
ther treatment. To give a more complete account of stamineal tissue, 
mention also should be made of the anther tube. At first the filament 
develops slowly and the stamens are distinct from one another, but 
just preceding the unfolding of the flower bud the filament gains 
length at a very rapid rate by the elongation of its cells; finally the 
lateral edges of the anthers become coalescent, thus forming a tube, 
which, when the flower is fully developed, projects beyond the tubular 
corolla. The anthers do not simply cohere, but unite, for cross sec- 
