Siete Mt tal Shee Sah nD can 
ci aes ON a aio Nn A 
a a ect Lt 
* 
148 BOTANICAL GAZETTE. [ June, 
between the leaves and the axis, it is objected that some 
terminal flowers are irregular, and many axillary flowers are 
regular. 
The fifth stamen of didynamous flowers is partially or 
totally aborted, and is found in the plane of greatest press- 
ure. But this stamen, if developed, would occupy the place 
of the style, and might defeat the contrivances for cross- 
_ fertilization, so that this abortion may also be referred to 
functional causes.’ Admitting the association of the two sets 
of causes, which ought to be regarded as having more influ- 
ence? Citing the case of Pentstemon and Jacaranda, in 
which the fifth stamen is even more strongly developed than 
the others, though not antheriferous, he says: ‘* Behold, in 
a case the biological cause has triumphed over the mechan- 
aeake; 
_ may be atftibuted to the action of mechanical causes, from 
‘upper lip is strongly developed. 
__ We substitute natural selection, we shall have a known causes 
Only on variations which involve a functional advantage. 
g, however, to observe that even teleolog- 
m ; yiews 
: ing 
. r zygomorphy, while igno™ 
Ec aciechve influence of insects ; for it is snconceivable that 
y Cause, such as gravitation, should operate in such a reg 
air and maintain an adjustment to etn 
: - Suppose an insect lights on the stamen 
ore a of an horizontal flower, how can gravitation have 
power to facilitate fertilization by turning these organs 
* This abortion i ers, 
434) and Lubbock ase tttibuted to natural selection by Miiller (Fertilization of Flowers, 
bb (Brit. Wild Flowers in Relation _= ding 30), oe ; 
