68+ THE POPULAR SCIENCE MONTHLY. 



ment be again offered to the same leaf, will it be able to digest a sec- 

 ond 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 strange- 

 ness 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 begin- 

 ning of its existence. Albumen, a substance particularly rich in nitro- 

 gen, 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 fur- 

 thermore been found that the action can be made a continuous one. 



Let us now leave the domain of plants and enter into that of ani- 

 mals, 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 



