290 General Notes. [ April, 
because it would be more trouble to get at their nectar in any 
other—its more ravenous appetite and greater dependence upon 
plant-food are the only causes which render its visits more fre- 
quent than those of less-specialized insects, and its value to the 
plant greater; for visit for visit, they are as effective in fertilizing 
the flowers as it is. Such flowers as those of Thymus serpyllum, 
which are only slightly modified, are not as a rule perforated ; nor 
are pendant flowers like those of Campanula rapunculoides. But 
of bee-flowers like those of Aconitum napellus very few are visited 
regularly before a systematic perforation of their corollas is 
begun. In a few other cases where this bee either leaves the 
nectar untouched or obtains it by force it collects pollen, and in 
so doing aids in the fertilization of the flowers 
Were we only to count the flowers which this bee visits in the 
normal way, and those which it perforates, we might infer that its 
good and evil deeds stand pretty evenly balanced; nevertheless it 
would always remain a disteleologist because it seldom uses its 
own organs ina way corresponding to the completeness of their de- 
velopment, and, moreover, breaks ruthlessly through the most 
highly developed floral structures, so that to a certain extent 
both its own organs and those of the flower are rendered useless. 
But to fully appreciate its injuriousness we must note how great- 
ly it prefers those richly nectariferous flowers which it perforates 
to those with less nectar which it visits normally. So great is 
this preference that it is astonishing to see how few flowers of 
such species as Salvia pratensis remain unperforated. 5 
Bad in itself, this habit of perforating flowers is rendered still 
worse for the plants by the habit which certain other insects have 
of obtaining nectar through openings already formed, though 
they would not form any for themselves. This limits still more 
the number of useful visitors of the flowers. Hence it is not im- 
probable that this bee may have been the cause of the extinction of 
many alpine plants; and one can scarcely doubt that changes in 
flowers which tend to check or stop perforation by it have been 
taken up and developed by natural selection from the time when 
this unnatural action first began. An instance of partial protec- 
tion against this bee is afforded by Rhinanthus alectorolophus, 
where the inflated calyx and the firm, smooth arch of the corolla 
together protects the flowers from forcible removal of their 
nectar, and force the bee to aid in their fertilization or go without 
the sweets. In Pedicularis verticellata the perforation of the floral 
envelopes is partially prevented by the globular form of the calyx, 
the abrupt, rectangular bend of the corolla within, and its smooth, 
laterally compressed condition without the calyx. 
It is easily seen why rudimentary organs are not formed in 
flowers robbed of their nectar by our bee; for bee- and butterfly- 
flowers which are thus treated either receive enough visits from 
other species to ensure their fertilization and prevent the abortion 
