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TEE POPULAR SCIENCE MONTELT.^-SUPPLEMEFT. 



Reptiles of serpentine or lizard like form crawled 

 through their dense underbrush of club-moss and 

 lichens ; while primitive scorpions, beetles, and 

 cockroaches, eked out a hard-earned livelihood by 

 devouring smaller prey, or by feeding on the more 

 succulent parts of the dry and horny plants around 

 them ; but not a single moth or butterfly flitted 

 among the primeval tree-ferns and pines, as they 

 flit in countless myriads now on the banks of the 

 Amazon or the mountain-slopes of Ceylon and Ja- 

 maica. 1 The higher and brighter forms of insect- 

 life are entirely dependent upon the honey or oth- 

 er secretions of flowers, and without flowers they 

 could not continue to exist for a day, much less 

 come for the first time into existence. 



As soon, however, as any flowering plants at all 

 began to show themselves on the face of the earth, 

 if only in the form of cones or green panicles, we 

 may be sure that they were visited for the purpose 

 of feeding by some of the smaller insects of those 

 days. The pollen and other parts of the incipient 

 blossom would almost certainly attract attention 

 both by their softness and their nutritious prop- 

 erties. We shall see hereafter, when we. come 

 to examine the case of fruits, that those very 

 portions of plants which are devoted to the 

 growth of their offspring are the exact portions 

 best fitted for animals to devour and thrive 

 upon. And as the insects would carry away 

 small quantities of the pollen, adhering to their 

 legs and heads, they would be very likely to 

 deposit some part of it on the stickier portion of 

 similar blossoms which they afterward visited. 

 Any flower that offered exceptional advantages to 

 such visitors in the way of food, would thus be 

 able to substitute the new mode of fertilization 

 by means of insects, for the old one by means 

 of the wind. Moreover, this substitution would 

 prove economical to the plant, because wind-fer- 

 tilized flowers require a large number of stamens 

 and pistils, hanging out in conspicuous situations, 

 so that the pollen may be borne away upon the 

 breeze in sufficient quantities to fertilize a large 

 proportion of the neighboring blossoms. Of 

 course such a system is comparatively wasteful 



1 Those readers who have personally made acquaint- 

 ance with tropical scenery will be able to recogDize 

 in the picture of green forests given above a strong 

 family likeness to the existing vegetation in the warm- 

 er zones of our earth. It is a great mistake to sup- 

 pose that the tropics are noticeable for their brilliant 

 coloring. Here and there, under exceptional circum- 

 stances, one may liirht upon a solitary tree covered by 

 huge scarlet or yellow flowers, of a kind which we sel- 

 dom see in temperate climates; but the general as- 

 pect of a tropical hill-bide is that of monotonous and 

 wearisome verdure. 



and expensive to the parent-plants, since they 

 are obliged to produce vast quantities of pollen, 

 which will be dissipated ineffectually by the wind, 

 and vast quantities of ovules, which are never 

 destined to receive the quickening influence of 

 the pollen. Now, every device which enables a 

 plant or animal to perform any one of its neces- 

 sary functions at a less physiological cost than 

 formerly, will obviously leave it a greater surplus 

 of energy to be expended in other directions, 

 and will thus prove of use to it in that long and 

 ceaseless struggle which eventuates in the sur- 

 vival of the fittest. Accordingly, if any special 

 combination of circumstances at any particular 

 time happened to give one plant such a structure 

 that its pollen was specially sheltered from the 

 wind and specially attractive to insects, while at 

 the same time its ovules were placed within a 

 specially sticky receptacle, adapted to retain any 

 pollen-grains which might fall upon it — then that 

 plant and its descendants would enjoy such ex- 

 ceptional advantages as would enable them to 

 live down their less fortunate neighbors, and to 

 become the ruling vegetable races of the world. 

 What might be the special causes which first 

 gave rise to such a structure we can hardly even 

 conjecture; but that they did occur, and, having 

 occurred, produced the result above sketched out, 

 we know with a considerable degree of certainty 

 from the mere inspection of Nature as it unfolds 

 itself to inquiring eyes at the present day. 



So soon as certain plants have thus begun to 

 depend upon the visits of insects as a means of 

 fertilization, a competition will naturally spring 

 up between them for the favor of their little 

 guests. Hence it will happen that any flower 

 which has in its neighborhood patches of bright- 

 colored leaves, or which disperses odorous parti- 

 cles from its surface, will be benefited by the ad- 

 ditional attractions it offers, and will be oftener 

 fertilized, on the average of cases, than any less 

 alluring blossom. But how will these colors ori- 

 ginally present themselves ? I believe it was 

 Mr. Herbert Spencer who first pointed out that 

 the undeveloped leaves at the ends of a long 

 shoot have a great tendency to assume a reddish 

 or purply hue ; and that such terminal bunches 

 are exactly the places where inflorescence oc- 

 curs. Long before, Wolff and Goethe had shown 

 that the flower consists essentially of several 

 whorls of aborted or oddly-developed leaves. 

 And Mr. Spencer suggested that, wherever such 

 colored immature shoots contained the seed- 

 producing organs, they might offer an addition- 

 al means of attracting insects, and might thus 



