That this is really the case seems to be implied in the following paragraph which I quote from the same interesting work that I have before referred to[87] “The conclusions that we draw from the study of this genus differ in the most striking manner from those of Fabre. The one pre-eminent, unmistakable, and ever-present fact” (the invariable fact, as one might say) “is variability. Variability in every particular—in the shape of the nest and the manner of digging it, in the condition of the nest (whether closed or open) when left temporarily, in the method of stinging the prey, in the degree of malaxation, in the manner of carrying the victim, in the way of closing the nest, and last and most important of all, in the condition produced in the victims of the stinging, some of them dying and becoming ‘veritable cadavers,’ to use an expressive term of Fabre’s, long before the larva is ready to begin on them, while others live long past the time at which they would have been attacked and destroyed if we had not interfered with the natural course of events. And all this variability we get from the study of nine wasps and fifteen caterpillars”![87] Fabre’s ideas therefore seem totally disproved, but though natural selection—the counter-theory to his own—has no doubt produced the _Sphex_ and _Ammophila_, with their habit of stinging and storing caterpillars, to serve as food for their young, it does not follow that it has done anything more than this; for though variation be the stuff in which natural selection works, it need not always work in it—any more than a tailor need always make clothes because there is an abundance of cloth. ------------------------------------------------------------------------ [Illustration: SOLITARY WASPS] In the upper part of the picture a solitary wasp is seen attacking a caterpillar on a leaf. Beneath is another of the same species busy pounding the entrance to its burrow with a pebble.