238 BIOLOGY. 



1224. Nature can produce no originally octo-, deka-, 

 or dodeka-petalous, &c. corolla. 



1225. Corollse with originally nine, eleven, and more 

 numbers are not impossible. The last seem only to 

 exist. 



1226. All corollas having even numbered petals, ori- 

 ginate through arrest of the odd leaflet. 



1227. The number two originates most usually and 

 in the simplest manner from the arrest of the number 

 three. If it originates from the quinary quantity, two 

 pinnate leaflets are then coarrested. 



1228. The aberration is recognized either from the 

 position of the lobes or petals that have been left remain- 

 ing, or from comparison of the number in other parts, in 

 the calyx and capsule. 



1229. The quaternary corolla is a quinary without the 

 uneven leaflet. 



1230. The hexapetalous is a doubling of the tripe- 

 talous, corolla. There are two whorls of petals, provided 

 the calyx has not become corolla-like in character. Both 

 cases are demonstrable through the alternating arrange- 

 ment of the parts. 



1231. The number eight is a doubled four. 



1 232. Nine is indeed in most instances a product of 

 three multiplied by three. 



1233. The number ten is a doubled five. 



1234. In every number of petals the law of unequal 

 development consequently prevails. 



1235. The original arrangement of the parts of the 

 corolla is bilateral, and therefore symmetrical. In the 

 papilionaceous corollse this originally symmetrical arrange- 

 ment is most perfectly maintained. They repeat the posi- 

 tion of their pinnate leaves. 



1236. This symmetrical arrangement is shown even 

 in many tubular, as in the labiate and personate, corollae. 

 The trifid lower lip is the standard and wings ; the bifid 

 upper lip, on the contrary, the keel. 



1237. The small liguliform petal of the lettuce's 

 corolla is a tubular corolla entirely slit up ; it is therefore 

 mostly quinque-dentate. 



