266 NATURAL HISTORY OF THE FARM 
arrangement is doubtless most convenient for the visitors; 
it is the one most commonly adopted, and most successful. 
And as there are groceries that cater to a select and limited 
patronage, so there are flowers that put their nectar out of 
reach of common visitors, and reserve it for those that 
are epecially endowed—not with long pocketbooks, but 
with Icng proboscides. They secrete their nectar at the 
bottom of deep and narrow corolla tubes or spurs, or behind 
barriers of sharp offensive spines, or glandular hairs. The 
nectar of certain 
trumpet-like con- 
volvulus flowers can 
be sucked only by 
long-tongued hum- 
ming-bird moths. 
That in the tightly- 
closed bilabiate 
corollas on the mon- 
key-flowers can be 
Fic. 107. Beard-tongue (Pentstemon pubescens) a, the had only by bum- 
Hie beaded Gncer tren whieh te dedined oo kat ; 
ee ee 
Se ee 
“General Biology.) the mouth of the 
corolla and enter. 
So, when we watch the flower-clumps in the fields, we shail 
see but few visitors about such specialized flowers as turtle- 
heads (fig. 103), and butter-and-eggs, while the outspread 
tables of open corollas of such as meadowsweet (fig. 104) 
and wild carrot are thronged with visitors of many sorts. 
The colors of summer flowers are in themselves very 
beautiful and satisfying. Their forms are wonderfully varied 
and interesting. But colors and forms are alike increasingly 
instructive when we learn what roll they fill in the drama of 
life. And we shall enjoy our contact with nature better 
