Just what natural enemy the trap-door spider has I do not know. I never saw a nest that had been broken into or in any way disturbed, except those which we had disturbed in our observations.
IV. THE DESERT NOTE
I often wonder what mood of Nature this world of cacti which we run against in the great Southwest expresses. Certainly something savage and merciless. To stab and stab again suits her humor. How well she tempers her daggers and bayonets! How hard and smooth and sharp they are! How they contrast with the thick, succulent stalks and leaves which bear them! It is a desert mood; heat and drought appear to be the exciting causes. The scarcity of water seems to stimulate Nature to store up water in vegetable tissues, just as it stimulates men to build great dams and reservoirs. These giant cacti are reservoirs of water. But why spines and prickles and cruel bayonets? They certainly cannot be for protection or defense; the grass and other vegetation upon which the grazing animals feed are not armed with spines.
If the cacti were created that grazing animals in the desert might have something to feed upon, as our fathers' way of looking at things might lead us to believe, why was that benevolent plan frustrated by the armor of needles and spines?
Nature reaches her hungry and thirsty creatures this broad, mittened hand like a cruel joke. It smites like a serpent and stings like a scorpion. The strange, many-colored, fascinating desert! Beware! Agonies are one of her garments.
All we can say about it is that Nature has her prickly side which drought and heat aggravate. In the North our thistles and thorns and spines are a milder expression of this mood. The spines on the blackberry-bush tend against its propagation for the same reason. Among our wild gooseberries, there are smooth and prickly varieties, and one succeeds about as well as the other. Apple-and pear-trees in rough or barren places that have a severe struggle for life, often develop sharp, thorny branches. It is a struggle of some kind which begets something like ill-temper in vegetation—heat and drought in the desert, and browsing animals and poor soil in the temperate zones. The devil's club in Alaska is one mass of spines; why, I know not. It must just be original sin. Our raspberries have prickles on their stalks, but the large, purple-flowering variety is smooth-stemmed.
Mr. John C. Van Dyke in his work on the desert expresses the belief that thorns and spines are given to the desert plants for protection; and that if no animal were there that would eat them, they would not have these defenses. But I believe if there had never been a browsing animal in the desert the cacti would have had their thorns just the same.
Nature certainly arms her animal forms against one another. We know the quills of the porcupine are for defense, and that the skunk carries a weapon that its enemies dread, but I do not believe that any plant form is armed against any creature whose proper food it might become. Cacti carry formidable weapons in the shape of spines and thorns, but the desert conditions where they are found, heat and aridity, are no doubt their primary cause. The conditions are fierce and the living forms are fierce.
We cannot be dogmatic about Nature. From our point of view she often seems partial and inconsistent. But I would just as soon think that Nature made the adobe soil in the arid regions that the human dwellers there might have material at hand with which to construct a shelter, as that she gives spines and daggers to any of the vegetable forms to secure their safety. One may confute Mr. Van Dyke out of his own mouth. He says: