136 ABOUT ORCHIDS. 
but civilized mankind has not yet done wondering 
at it. The stately growth, the magnificent green- 
white flowers, command admiration at a glance, 
but the “tail,” or spur, offers a problem of which 
the thoughtful never tire. It is commonly ten 
inches long, sometimes fourteen inches, and at 
home, I have been told, even longer; about the 
thickness of a goose-quill, hollow, of course, the 
last inch and a half filled with nectar. Studying 
this appendage by the light of the principles he 
had laid down, Darwin ventured on a prophecy 
which roused special mirth among the unbelievers. 
Not only the abnormal length of the nectary had 
to be considered ; there was, besides, the fact that 
all its honey lay at the base, a foot or more from 
the orifice. Accepting it as a postulate that every 
detail of the apparatus must be equally essential 
for the purpose it had to serve, he made a series of 
experiments which demonstrated that some insect 
of Madagascar—doubtless a moth—must be 
equipped with a proboscis long enough to reach 
the nectar, and at the same time thick enough at 
the base to withdraw the pollinia—thus fertilizing 
the bloom. For, if the nectar had lain so close to 
the orifice that moths with a proboscis of reason- 
able length and thickness could get at it, they 
would drain the cup without touching the pollinia. 
