146 Natural Theology. 



middle of her proboscis is becoming covered with 

 the pollen from its short stamens, to fertilize the 

 plants with short pistils. But the most remarkable 

 cases of special adaptation are found among the 

 orchids which have been so carefully studied by 

 Darwin. Many of the species cannot possibly fer- 

 tilize themselves, and if shut out from insects, fail 

 to produce seed. One, the Orchis fyramidalis, may 

 be taken as a type of many in its special adaptations 

 by which its structure and functions, the structure 

 and instinct of the insect, are all combined to pro- 

 duce the needed result. The structure of the flower 

 is such that the proboscis must enter in a given di- 

 rection ; this brings it in contact with the packets 

 of pollen that adhere to it by a viscid fluid, that has 

 the chemical property of rapidly becoming solid 

 when exposed to the air. The packets of pollen 

 bend over as they dry, so as to take the exact posi- 

 tion they ought to take to strike the stigmas of the 

 next flower. Those stigmas are covered with a 

 viscid fluid to which the grains of pollen adhere, and 

 the work is done. What a complicated arrangement 

 is here, and yet how perfect the result ! First, there 

 is the form of the flower that guides the proboscis 

 aright ; second, the position of the pollen packets all 

 ready to be withdrawn ; third, the glue by which 

 they are firmly fixed to the proboscis ; fourth, their 

 hygrometric action, by which in drying they bend 

 just far enough to bring each one in contact with 

 the two stigmas of the next flower the insect visits ; 

 and lastly, the glue upon the stigmas sufficiently 



