FLOWERS AND INSECTS 
9 * 
the Silenoideae (Caryophyllaceae) with shorter tubes (such 
as Gypsophila), Geranium, Epilobium, Rubus, Polemonium, 
Veronica, Mentha, Calluna, &c. Some of these attain their 
purpose by concealing the honey with the stamens, &c., 
others by aid of the calyx, which shows a further advance in 
being gamosepalous. Others again are more deeply peri- 
gynous, the receptacle becoming more deeply hollowed and 
tubular, whilst in the four genera last mentioned we find the 
new and important phenomenon of a sympetalous corolla. 
The visitors to flowers of this type are the smaller bees, 
many Lepidoptera, and the long-tongued flies, with a few of 
the larger bees. Comparing the flowers of class B with 
those of class A, we see that they have gained in the pro- 
tection of the honey, pollen, carpels, &c., but at the expense 
of losing the visits of the shorter-tongued insects. This loss, 
however, is more than compensated for by the superior 
cleverness and activity of the longer-tongued visitors ; the 
latter, too, are usually found to confine their visits during one 
flight to few or even to one species of flower, so that much 
less pollen is wasted by them than by the more stupid insects 
which visit flowers more indiscriminately. The advantage 
to an insect of keeping (as bees largely do) to one kind of 
flower as long as possible, is evident, for the insect will, so 
to speak, ‘get its hand in’ for the particular flower, and be 
able to visit far more flowers in a given time than if it 
frequently changed from one species to another. 
A few of the Campanulaceae, most Dipsaceae, and the 
Compositae have flowers with depth of tube, &c. as in class B, 
but as they have aggregated inflorescences and are thus more 
attractive to insects, besides being on a higher level in other 
biological features, they are grouped together as a class B' 
(“ flowers with fully concealed honey, in aggregated in- 
florescences ”). 
A further lengthening of the tube of the flower, beyond 
the stage we have considered, will exclude the shorter- 
tongued insects and allow only bees and Lepidoptera to get 
the honey. The highest stage in this line of evolution is seen 
in many flowers of class F (Lepidoptera flowers). Silene 
(the longest-tubed forms, like S. inflata , nutans , &c.), Lychnis, 
&c., have a gamosepalous calyx, Oenothera, Daphne sp., 
Cuphea, &c., a long tubular receptacle, some Rubiaceae, 
