THE REV. G. HENSLOW ON THE ORIGIN OF FLORAL ASTIVATIONS. 191 
D. Anomalous :—1 leaf external, the other 2 equitant. 
Crocus. 
A. Examples of the reversal of spiral in the inner whorl as compared with the outer. 
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B. Example of both whorls being right-handed, 
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C. Examples of both whorls being left-handed. 
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D. Both whorls convolute to the right. 
E. Outer whorl imbricate proper, inner convolute. Sometimes both to the right, and 
sometimes both whorls to the left. 
IX. Note А.--Ох THE SYMMETRY oF A CRUCIFEROUS FLOWER. 
It has been customary hitherto to refer the structure of a cruciferous flower to a 
binary or quaternary type, though in different ways * But, seeing that the leaves аге so 
generally pentastichous, I would suggest a reference to an original quinary arrangement, 
with a subsequent symmetrical reduction by the arrest of the fifth member of each 
Whorl; by which it will be seen that the relative positions of the organs as they occur in 
а cruciferous flower can readily, but of course theoretically, be accounted for. Thus, 
if the sepals be supposed to be arranged quincuncially, then the external position of the 
the anterior and posterior sepals will immediately follow, these being numbers 1 and 2 of 
quincunx. (Compare the figs. 13 and 16 of Tab. XXV.) Next, assuming the Ist of the 
five petals to lie between the 1st and 4th sepal (for the whorls must alternate), and the 
lst of an outer whorl of five stamens to lie between the 1st and 4th petals, we shall have 
the 1st and 2nd retained as stamens (forming the two exterior lateral and lower ones), 
and the 3rd and 4th (opposite the anterior and posterior sepals) arrested or represented 
by glands. 
. The next whorl of stamens arising in a similar manner, it will be seen how the 1st and 
4th will form, by approximation, one pair, the posterior, and the 2nd and 3rd the other 
pair. Lastly, the pistil is probably composed, as has been often suggested, of four 
carpels; but their union, according to my hypothesis, would be as follows. The two 
posterior carpels, numbers 1 and 4, coalesce to form the posterior half of the pistil, 
while the 2nd and 8rd, uniting in front, will form the anterior half. Thus two coherent 
* A summary of the various theories шау be found in Le Maout and Decaisne’s ‘ Botany,’ pp. 229, 230. See also 
* Note sur une monstruosité de la fleur du Violier (Cheiranthus Cheiri, І.) par M. P. Duchartre, Ann. des Se. Nat., 
õme série, xiii. р. 315. 
