Show How the Thlitla Der ends Itself On the other hand the thistle family are far more truly rural and agricultural agricul-tural in their habits being denizens of the open fields and readily accommodating accommo-dating themselves to an vacant situations situa-tions Hence they have only felt the need of arming themselves in a rough andready prickly fashion against the probable assaults of their natural enemies They have forged darts but I have not learned to poison them Their prickly leaves and wings are amply sufficient suf-ficient for defense without the necessity for developing a virulent juice to be injected into the very veins of their savage aggressors Natural selection can never posh any special line of evolution evo-lution further than is imperatively called for by the wants and circumstances circum-stances ot the particular species It always necessarily leaves off just at the point where the protection afforded is fully sufficient to guard the kind from the possibility of extinction The thistles have found in actual practice that prickles alone are quite enough to secure their boasted immunity from extraneous attacks the nettles have practically discovered for themselves that without stings they would soon be landed in the final limbo of utter nonentity Mr Grant AUenin PujHtlar Science Monthly for November I |