258 General Notes. [ April, 
spects, they can cease to visit them, and by this means cause their 
deterioration and final destruction through self-fertilization, while 
such as meet their wants are strengthened by repeated crossing. 
Here, then, we have to deal with something more than natural 
selection proper, namely, a methodical though unconscious eae 
tion by the insects. A most interesting question, and one well 
treated by Dr. Müller in his papers, is the following: *“ What 
peculiarities of flowers are to be attributed to insect-selection, and 
what to natural selection ?” 
When an anemophilous flower begins to become entomophilous, 
the first step is one tending to cause insects to come in contact 
with its stamens and pistil; and this is either the secretion of nec- 
tar in both forms of the unisexual flowers, or the union of the 
sexes to form a perfect flower. Adhesiveness of the pollen must also 
be developed in order to insure its transfer by insects from one 
flower to another. Nectar, being of great value to insects, and 
not directly useful to the plant, should be considered the result of 
insect-selection ; but the adhesiveness of the pollen, being of im- 
mediate value to the plant, and only utilized in comparatively 
recent times by insects, should be considered as a result of nat- 
ural selection. We must suppose that at first all flowers were 
insects joined to natural selection wrought great changes, whereby 
the flowers were so modified as to adapt them to the visits of 
special groups of insects, which themselves experienced, by nat- 
ural selection, changes fitting them to profitably visit the modified 
flowers. 
r. Müller sums up the entire matter as follows: 1. All wild 
flowers are the result of the combined action of two different 
sorts of selection. Those E A (such as attractive colors, 
odor, sheltered retreats, food, and the means of protecting this 
latter product against bidia guests) which are immediately _ 
useful only to the insects which visit the flowers, are usually the 
result of the selection exercised by these insects themselves ; but | 
such peculiarities as are immediately useful only to the plant (the 
securing of crossing when insects visit the flowers, and of self- 
fertilization when they do not, and the protection of the repro- 
ductive organs against inclement weather and enemies) have been 
developed by natural selection, acting quite independently of the 
insects; finally those which are equally useful to both flowers and 
insects are the result of the combined action of both sorts of 
selection. 
2. The first flowers were, for the most part, simple, regular and 
open, and were subjected to a mixed company of insect visitors, 
which succeeded in rendering permanent only conspicuous colors, 
odor, and nectar, 
4. From this original mixed group, the carrion-loving Diptera, 
