on species and varieties, by reason of which, when published, "I dare say I shall stand infinitely low in the opinion of all sound naturalists." The papers referred to were the treatise on cirripedes, to which eight years, instead of the "some months" he had anticipated, were devoted. The importance of this labor was not fully appreciated at the time—"I hate a barnacle," he said once in his weariness over the task, "as no man ever did before, not even a sailor in a slow-sailing ship"—but Sir Joseph Hooker has written to Mr. Francis Darwin: "Your father recognized three stages in his career as a biologist: the mere collector at Cambridge; the collector and observer in the Beagle, and for some years afterward; and the trained naturalist after, and only after, the cirripede work. That he was a thinker all along is true enough, and there is a vast deal in his writings previous to the cirripedes that a trained naturalist could but emulate. . . . He often alluded to it as a valued discipline, and added that even the 'hateful' work of digging out synonyms, and of describing, not only improved his methods but opened his eyes to the difficulties and merits of the works of the dullest of cataloguers. One result was that he would never allow a depredatory remark to pass unchallenged on the poorest class of scientific workers, provided that their work was honest, and good of its kind. I have always regarded it as one of the finest traits of his character—this generous appreciation of the hod-men of science, and of their labors, . . . and it was monographing the barnacles that brought it about."
Darwin's letters, during the time he was engaged upon the "Origin of Species" and the related works, reveal the minute care with which he examined every trifle of a detail, and sought information from every possible quarter. Here we see him inquiring of Mr. Fox how early the tail-feathers of young fantail pigeons are developed, and remarking upon the difference in the weight of the foot or the wing of a wild and a tame duck. He wants to ascertain whether the young of our domestic breeds differ as much from one another as do their parents, and has no faith in anything short of actual measurement and the rule of three. He asks for lizards' and snakes' eggs to see whether they will float on sea-water, and whether they will keep alive thus floating for a month or two in his cellar.
In similar experiments on seeds he is so full of exultant anticipation that he will discover something that will conflict with Hooker's views, that the children are asking him often whether he shall beat Dr. Hooker; and when the seeds have germinated after a salt-water soaking that ought to have killed them, he has pangs of conscience and of vexation because the botanist seemed "to view the experiment like a good Christian." Then he acknowledges Hooker to be a good man to confess that he expected the cress—which vegetated after twenty-one days' immersion—would be killed in a week, "for this gives me a nice little triumph." But he is also making experiments at which Hooker would have a good right to sneer, "for they are so