FRUITING. 125 



possihilily of any such operation, but more recent discoveries 

 show these plants to exhibit most beaulilul examples of this 

 iiTra'.)iivmcnt. 



In i.'je Asclepiadere, the stigma is a fles'hy, tn e-cornered 

 disk, having a gland on each angle. To each gland there is 

 attached a pair of yellow baj^s, containing the pollen and 

 caliod polU n nwssf's. 'I'liese do not opeti, and the stigma has 

 no ijjcretini' siutace. In these circmnsliinccs, the imi)rc2nxi. 

 tion of those planis otiered an important jjroblem for solution, 

 Ehrenborg found tlial tiirough one side, that next the stigma 

 of these pollen manes, pollen tubes were emitted, and directly 

 entered the stigma, and made their way to the ovary, as in 

 other cases, thus siiowing the perfect agreement in this case, 

 at least, with other |)hanerogamous plantr. It has also prov- 

 ed more tlian probable, that similar arrangcfuents accom- 

 plisli the same end in Orcliiucce In orthotropous plants, 

 threads in some cases han^ down in the cavity of the ovarv 

 through which the pollen can pass into the foramen. In oth- 

 er cases, the conducting tissue elongates so as to reach the 

 foramen during the time of tertilization. In Eu()horbia, the 

 apex of ihe nucleus is protruded lar beyond the foramen, so 

 as to lie within a kind ot hood like expansion of the placenta. 



Section 4. Fruiting. 



157. Hy fruiting we understand the changes the ovarium and 

 its connected parts undergo in arriving at maturity. We have 

 already noticed the changes which take place in the contents 

 of the ovarv. The chanijes of the other floral orji-ins, in ma- 

 ny cases, are no less prompt and distinct. The floral envel- 

 ops soon wither, unless connected with the ovary; the stam- 

 en falls ofl*, the pistil dries up or iiardens when composed in 

 part of t!ie axis «>fthe plant, and all the energies of the plant 

 seem to 1)0 directed to the p'.'rfeclion of the fruit or ovary. 

 That these chaniies are efTected bv the act of fertilization, 

 may be mad<; manifest by preventing the access of the 

 pollen to the p'sti!, and the parts will for a much longer time 

 rruiain unchanirnd. There S( em to be two ditVerent courses 

 taken in the perfection ofditTtirent fruits. In one, the ovary 

 l)ecomes dry, hard, membrmeous or woody as in tljc Poppy, 

 C —^' I, <8cc. In others, the ovarv becomes floshv, affording 

 - agreeable articles of t'ood, as aj)ples, pears, peaches, 

 mcIlons.Acc. Tnis has been supposed to depend upon the number 

 ofstomites on thes irface of the ovarv. In the drv one, the 

 stomates were suflicienl to i>ermit the evaporation of all the 



11* 



