Page:Popular Science Monthly Volume 30.djvu/706

684 be again offered to the same leaf, will it be able to digest a second time? Yes; but the process of digestion is much more tardy, and, if the plant outlive this exertion, it certainly perishes in making a third or fourth attempt. Too large a quantity of food will kill the plant immediately. This property, apparently so startling a one in plants—namely, their being capable of digesting animal food—loses in strangeness if we look about us more carefully in the vegetable kingdom. There we find not unfrequently this power of digesting nitrogenous—i.e., animal substances, or at least of changing them from a solid to a more soluble condition. For instance, the seeds of many plants store up food for the purpose of nourishing the young plant in the beginning of its existence. Albumen, a substance particularly rich in nitrogen, is first changed into soluble material by the young bud, and is then by degrees absorbed, or, in other words, digested. Other plants possess similar dissolving juices, but up to the present it has not been ascertained what advantages the plant derives from their possession.

Five grammes of the milk-juice of the fig, diluted with sixty grammes of water, will dissolve ten grammes of fibrin in twelve hours, and in a month's time can gradually digest as much as ninety grammes. In this respect the "melon-tree" (Carica papaya), a small tree of South America, has, above all others, claimed the attention of botanists. A few drops of the milk-juice, which fills all parts of this tree, are said to soften in a short time the meat of even old animals, and if we may credit the tales some travelers tell, it is sufficient to roll the meat up in these leaves for several hours to render it soft and palatable. From the milk-juice of the Carica there has been obtained a compact substance called "papaiine," three grammes of which will dissolve one hundred grammes of fibrin in two days, and it has furthermore been found that the action can be made a continuous one.

Let us now leave the domain of plants and enter into that of animals, so much more varied in number and form. We shall still fancy ourselves in the kingdom of flowers when we turn our attention to those variegated beings which cluster about the subaqueous rocks in wild profusion. There seem to be brilliant flower-calyxes of hyacinths, carnations, anemones, gently rocked to and fro by the water—calyxes which, even had they grown under the genial warmth of sunlight, could hardly bloom more beautifully. But should one try to gather a bouquet from among these magic flower-beds, he would scarcely have touched a bud, when a sharp, stinging pain, more disagreeable than the burning of the nettle, would be felt. Even the sea-rose defends itself, and stings; very quickly it sends forth from their resting-place filaments charged with a corrosive fluid, filaments that, until then, had remained spirally incased like a spring wound up and ready for use. And how enormous is the number of these weapons of defense; some individuals are capable of sending forth six thousand millions! In the last century the plant-like nature of these sea-flowers was so generally