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1032 The American Naturalist. [December, 
BOTANY. 
Development of the Floral Organs in Aster and Solidago, 
—The point of growth of the shoot axis becomes very much retarded, 
and as a result the growing point is transformed into a broad, some- 
what elevated disc on which are to appear flowering capitula with 
centrifugal inflorescence. 
The first structure indicating an individual embryonic flower on the 
receptacle is a hemispherical outgrowth almost perfect in outline and 
becoming obconical as growth takes place. This embryonic tissue 
standing on a lateral axis, constitutes the foundation from which arises 
a differentiation of tissue into special organs. Thus far the path of 
embryonic development remains the same for all organs, even those 
of the most various kind. So we have the law of greater structural 
similarity well worked out in the earlier stages of organisms. From 
this condition of things on, a new departure is made; the apex of the 
broad flower axis ceases to grow, while the peripheral portion contin- 
ues to develop; here we have the first hint of the initial growth of 
true floral organs. A tubular ring is thus formed and on its periph- 
eral wall small papille rapidly arise, giving the structure a cup-shaped 
appearance with a shallow depression and scalloped margin. This 
so-called cup elongates, its sinus grows deeper, and the five corolla 
lobes become sharply defined and are known at once by their shape. 
Simultaneously with the development of the floral organs in the rising 
ring, in which there is a complete fusion of all flower parts until lib- 
erated, a deep central depression is forming, when ultimately the 
ovule-bearing portion is placed beneath the rest of the flower parts. - 
Thus we have an epigynous flower with an inferior ovary. However, — 
there are some who would substitute the word hypogynous for epigy 
nous, basing their argument on the theory that all the floral organs, 
in their initial state, are coalesced in the annular wall; that the 
appearance of each is due to the liberation of their uppermost parts; 
that each whorl may appear either in acropetal, or certain whorls, 
seemingly basipetal, order. ‘The real origin and behavior of the floral 
organs in their younger stages of development as correlated with the 
inferior ovary has attracted but little attention, and, therefore, 0 
definite statement can be made as to the true relationship aa 
between the floral organs in their embryonic condition. | 
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