The series of parasitic plants which have now been mentioned form a very interesting set. It must be pointed out that those which live merely on dead vegetable matter are "good" plants. They help on the quick and thorough employment of worn-out material.
Nor can we say off-hand that other parasites are "bad." They do kill other plants and do them harm, but then, are they not like a cattle-breeder who sends his inferior cattle to the butcher, keeping only those which are the very best of their kind? Perhaps these plants, by destroying the weak and unhealthy kinds, are doing a great deal of good.
Another interesting point about such parasites is that they are generally rare. They must be less common than their "host." Yet another is that they are all "degenerates." They show distinct traces of decay and bad development in their flowers and seed. That is also true in the case of parasitic animals.
Whether they do good or harm to the world of plants is doubtful, but there is no doubt that they are doing harm to their own chances!
CHAPTER XXVII
PLANTS ATTACKING ANIMALS
Brittle Star v. algæ—Fungus v. meal-worm—Stag-headed caterpillars—Liverwort v. small insects—Natural flower-pots—Watercups of Bromeliads—Sarracenia and inquiring insects—An unfortunate centipede—Pitcher-plants: their crafty contrivances—Blowflies defy them and spiders rob them—Bladderwort's traps which catch small fry—Hairs and their uses—Plants used as fly-papers—Butterwort v. midges—Its use as rennet—Sundew and its sensitive tentacles—Pinning down an insect—Suffocating and chloroforming the sundew—Venus' fly-trap which acts like a rat-trap—Have plants a nervous system?
ON the whole the animal world preys upon the vegetable world, and is in a way parasitic upon it. Indeed, the connexion between the two is very intimate—that of the diner and his dinner. One can scarcely imagine a more intimate connexion than this!
There are, however, a great many cases in which plants have turned the tables on their enemies and deliberately laid themselves out to catch and to destroy, to feed upon and to devour insects and small animals. One finds a few examples in almost every group of plants.
Thus there are certain green seaweeds or algæ which are said to attack and prey upon those peculiar sea-urchins known as Brittle Stars. The fungus which forms loops, acting exactly like a poacher's rabbit-snare, in order to catch mealworms, has been already mentioned.