604 THE POPULAR SCIENCE MONTHLY. 



present investigation, such as apples, plums, peaches, cherries, haws, 

 and bramble-berries. Every one of these plants is provided with hard 

 and indigestible seeds, coated or surrounded by a soft, sweet, pulpy, 

 perfumed, bright-colored, and nutritious covering, known as fruit. By 

 all these means the plant allures birds or mammals to swallow and dis- 

 perse its undigested seed, giving in, as it were, the pulpy covering as 

 a reward to the animal for the service thus conferred. But before we 

 go on to inquire into the mode of their development we must glance 

 aside briefly at a second important difference in the constitution of 

 seeds. 



If we plant a grain of mustard-seed in moist earth and allow it to 

 germinate, we shall see that its young leaves begin from the very first 

 to grow green and assimilate energetic matter from the air around 

 them. They are, indeed, compelled to do so, because they have no 

 large store of nutriment laid up in the seed-leaves for their future use 

 by the mother-plant. But if we treat a pea in the same manner, we 

 Ishall find that it long continues to derive nourishment from the abun- 

 dant stock of food treasured up in its big, round seed-leaves. Now of 

 course any plant which thus learns to lay by in time for the wants of its 

 offspring gives its embryo a far better chance of surviving and leaving 

 descendants in its turn, than one which abandons its infant plants to 

 their own unaided resources in a stern battle with the unkindly world. 

 Exactly the same difference exists between the two cases as that which 

 exists between the wealthy merchant's son, launched on life with abun- 

 dant capital accumulated by his father, and the street Arab, turned 

 adrift, as soon as he can walk alone, to shift or starve for himself in the 

 lanes and alleys of a great city. 



So, then, as plants went on varying and improving under the stress 

 of over-population, it would naturally result that many species must hit 

 independently upon this device of laying by granaries of nutriment for 

 the use of their descendants. But side by side with the advancing de- 

 velopment of vegetable life, animal life was also developing in com- 

 plexity and perfect adaptation to its circumstances. And herein lay a 

 difficult dilemma for the unhappy plant. On the one hand, in order to 

 compete with its neighbors, it must lay up stores of starch and oil and 

 albumen for the good of its embryos ; while, on the other hand, the 

 more industriously it accumulated these expensive substances, the more 

 temptingly did it lay itself open to the depredations of the squirrels, 

 mice, bats, monkeys, and other clever thieves, whose number was daily 

 increasing in the forests round about. The plant becomes, in short, 

 like a merchant in a land exposed to the inroads of powerful robbers. 

 If he does not keep up his shop with its tempting display of wares, he 

 must die for want of custom ; if he shows them too readily and un- 

 guardedly, he will lay himself open to be plundered of his whole stock- 

 in-trade. In such a case, the plant and the merchant have recourse 

 to the self -same devices. Sometimes they surround themselves with 



