UNVERIFIED DEDUCTIONS. 189 



found it eleven and a half inches long, with 

 only an inch and a half of nectar at the bottom. 

 He proved to his own satisfaction, by a study of 

 the structure of the flower, that it is fertilized 

 by moths that thrust their proboscides and heads 

 down into the flower to the utmost, and declared 

 that moths with proboscides long enough to 

 reach the nectar must exist in Madagascar. 

 "This belief of mine," he said, "has been ridi- 

 culed by some entomologists ; but we now know 

 from Fritz Miiller that there is a sphinx moth 

 in South Brazil which has a proboscis of nearly 

 sufficient length, for when dried it was between 

 ten and eleven inches long. When not pro- 

 truded, it is coiled up into a spiral of at least 

 twenty windings." The moth with the long 

 proboscis has not yet been discovered in Mada- 

 gascar; but the fact that there are moths else- 

 where with proboscides as long as the one 

 required in- the case of Angrcecum has removed 

 the improbability from the prediction. But the 

 point to be borne in mind is this, that the firm 

 conviction that orchids are fertilized by insects, 

 and that the flowers and insects are co -adapted 

 in structure, led Darwin to believe firmly in an 

 " improbable thing.*' l 



The questions raised in Darwin's mind by 



1 Fertilization of Orchids, pp. 162-166. 



