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THE POPULAR SCIENCE MONTHLY.— SUPPLEMENT. 



late family, represented by fool's-parsley, carrot, 

 and cow-parsnip, attain the same end in a slight- 

 ly different way. Their small white flowers are 

 grouped together in a flat mass, on the end of a 

 stiff stem, while the outermost blossoms of each 

 mass have much larger white corollas than those 

 of the central ones, thus affording a greater total 

 of attractive area. 1 But in the composite flowers 

 •we see this tendency pushed almost to its extreme 

 limits. These blossoms, of which the daisy is a 

 familiar example, consist of an immense number 

 of separate florets, crowded densely together into 

 a head, and inclosed by a bunch of bracts, known 

 as the involucre, which performs the same pro- 

 tective function for the compound mass as the 

 calyx performs for a separate flower. Each sin- 

 gle floret would doubtless fail by itself to secure 

 enough insect attention for safe fertilization ; but, 

 when thus huddled together into a conspicuous 

 head, they have proved very successful plants, 

 forming probably the largest and most populous 

 family of the vegetable kingdom at the present 

 day. 



If we look still closer at the individual mem- 

 bers of this last-named family, the composites, we 

 shall see yet more ingenious devices for attracting 

 attention by multiplied bunches, or by special ar- 

 rangement of florets. In the simplest form of 

 composite, which we find in the thistle and the 

 artichoke, all the florets are of the same size and 

 similarly colored. But in the centaury, the outer 

 florets begin to grow larger than their neighbors 

 of the central mass, thus affording a greater total 

 area of alluring color. In the corn-marigold, 

 again, the outer florets assume the shape of elon- 

 gated rays, but still retain the same yellow hue 

 as the central bells. Next, in the daisy, the rays 

 are of a brilliant white, and the central bells a 

 beautiful yellow ; while in the camomile, heads 

 composed of these twin-shaped florets are ar- 

 ranged in bunches, instead of growing each on a 

 separate stalk. These last-named heads closely 

 simulate the appearance of single blossoms, as 

 the long white rays which surround their clus- 

 tered central bells may easily be mistaken for 

 petals by a careless observer. There are two 

 other well-known composites which exhibit the 



1 1 cannot entirely agree with Mr. Ilerbert Spencer 

 that this difference is solely due to freer elbow-room 

 and more abundant light The case of a common Eng- 

 lish centaury, whose outer florets are sometimes much 

 larger than the inner ones, while at other times they 

 are of exactly the same size, shows that we must make 

 great allowances for the selective action of insects. 

 Were the effect due to position alone, it would occur 

 in all specimens alike. 



same tendency to increased conspicuousness in a 

 different way. The bunches of the milfoil, each 

 of which is separately too insignificant to attract 

 attention, are arranged on a number of umbels, 

 which make in the mass a compound head of 

 heads, while those of the golden-rod are disposed 

 on a tall shaft, so as to form a waving plume of 

 floret-bundles. To put it more simply, when in- 

 dividual flowers are too small to prove separately 

 attractive, they derive an advantage from group- 

 ing themselves into masses, and when the masses 

 thus composed become in turn too small for effec- 

 tive display, they succeed by once more grouping 

 themselves into compound bunches of masses. 



Before we conclude this lengthy investigation, 

 there is one more point upon which I should like 

 to dwell for a moment. While the colors of flow- 

 ers are apparently due in the main to insects, I 

 believe it to be equally true that the colors of in- 

 sects are indirectly due to the influence of flow- 

 ers. We observed above that any set of nervous 

 structures habitually excited in a certain manner 

 becomes thereby strengthened and improved, so 

 as to be capable in future of healthy and pleas- 

 urable stimulation. Now, as insects are perpet- 

 ually seeking their food among bright-colored 

 flowers, it follows that their eyes must have be- 

 come specially sensitive to the attraction of brill- 

 iant light. We get the extreme case of such 

 attraction in the mechanical infatuation which 

 draws the moth irresistibly into the burning em- 

 brace of the flame. We get it in a less violent 

 form among those nocturnal insects like the fire- 

 flies, which are provided with lanterns to guide 

 the opposite sex to their sides. And there seems 

 reason to believe that those insects which feed 

 habitually upon the beautiful flowers have ac- 

 quired a taste for color, which leads them to se- 

 lect mates resembling the flowers in hue. I hope 

 to enter more fully into this subject when we 

 come to treat of the development of fruits ; but 

 at present a brief outline of the principal facts 

 which support the theory now advanced may be 

 given shortly by anticipation. 



Among the invertebrates, there are no creat- 

 ures more exquisitely colored than the butter- 

 flies, which are flower-feeders. Those of tropical 

 countries are more brightly tinted than the deni- 

 zens of .northern climes, and exactly the same is 

 true of the flowers. In some special regions — 

 particularly islands such as Madagascar — the 

 flowers and the butterflies are both equally no- 

 ticeable for their brilliant hues. On the other 

 hand, if we look at their relations, the moths, 

 which are nocturnal in their habits, and feed often 



