BEES AND FT.OWERS. 475 



Figure 3 shows the delnils of an oi'chid : Tlu' arcal lip (7) of the 

 coroHa ends in a h)n<2,- spur which incloses I he neclar-proihicino- 

 organs (y^. Near (he i'ron( of the si)Ui- (he style exi)ands in(o 

 a double stigma, which hangs beneath the one large an(hei- (a). 

 Instead of being a diffused dust, (he grains of pollen are closely con- 

 nected and form two nuisses (/>(>), which are joined by the stipes (r) 

 to a glutinous body (fr) at the entrance of the spur. Except the 

 Oplii'ijs a pi f ('!■((, which, thaidvs to a si)ecial stnictuiv, can do so, the 

 plants of this family are utterly inca|)able of self fei'tili/atiou. 

 Nor can the wind aid them. The pollen gi-ains can easily be lifted 

 up with a needle oi' })encil i)oint from the glutinous mass where they 

 are collected. Tt is by an analagous process that honey bees effect 

 the cross-fei'tilization of these jdants. On entering the sjjur in 

 search of nectar they come into contact with the viscous disk (A) 

 and generalh' cai-ry off one or two of the pollen grains attached 

 somewhere (»n the front i)ortion of their body. As Darwin has 

 shown, the sticky substance dries very quickly and when the insect 



1 „ 2 



Fl(i. 4.— Trauspiirtation of orcbi<I polloii luassos r)y bocs. iPoUpii ropreseiitfd )iy diaKHiial 



lines.) 

 1. FAllenia <liwi<1iiit<i. 3. Eualnsxa rnrdiilci. 



enters the spur of another flower the mass is abandoned so that it 

 becomes attached to the stigma, where it yields the fertilizing element. 



The part that the insects play and the advantages of cross-fertiliza- 

 tion among the orchids are shown with all possible clearness in the 

 case of the vanilla. In Mexico this plant is fertilized naturally bv 

 different insects, especially by the Melipones, which greatly resemble 

 our bees, but in other regions artificial fertilization is produced by 

 rubl)ing the stamen on the pistil with a needle. INI. Tjecomte. who 

 has studied the matter, attributes the superior (pudity of the Mexican 

 vanilla to the advantage of natiii'al cr()ss-fer(ilization over artificial 

 auto-fertilization. In our own grwnhouses the vanilla plant has the 

 same experiences — it can produce flowers, but no seed, without pre- 

 liminary fei'tilization. 



We must therefore conclude that the Anthophila, and particularly 

 the Mellifera, have a place of no small im])()rtance in the fertilization 

 of flowering plants. They give them the advantages of crossing, and 

 in a large number of cases are al)solutely essential to their repro- 

 duction. 



