recognize a foreign egg at sight, or so easy-tempered as not to insist on straightway being rid of it; though this is no more inscrutable, it may be, than for another bird persistently, and as it were on principle, to cast her own offspring upon the protection of strangers; while this, in turn, is not more mysterious than ten thousand every-day occurrences all about us. After all, it is a wise man that knows what to wonder at; while the wiser he grows the stronger is likely to become his conviction that, little as may be known, nothing is absolutely unknowable; that in the world, as in its Author, there is probably "no darkness at all," save as daylight is dark to owls and bats. I did not see the oven-bird's eggs at

this time, however, my tender-hearted companion protesting that their faithful custodian should not be disturbed for the gratification of his curiosity. So we bade her adieu, and went in pursuit of a solitary vireo, just then overheard singing not far off. A few paces brought him into sight, and as we came nearer and nearer he stood quite still on a dead bough, in full view, singing all the while. When my friend had looked him over to his satisfaction,—never having met with such a specimen before,—I set myself to examine the lower branches of the adjacent trees, feeling no doubt, from the bird's significant behavior, that his nest must be somewhere in the immediate neighborhood. Sure enough, it was soon discovered, hanging from near the end of an oak limb; a typical vireo cup, suspended within the angle of two horizontal twigs, with bits of newspaper wrought into its structure, and trimmed outwardly with some kind of white silky substance. The female was in it (this, too, we might have foreseen with reasonable certainty); but when she flew off, it appeared that as yet no eggs were laid. The couple manifested

scarce any uneasiness at our investigations, and we soon came away; stopping, as we left the wood, to spy out the nest of a scarlet tanager, the feminine builder of which was just then busy with giving it some finishing touches.

It had been a pleasant stroll, I thought,—nothing more; but it proved to be the beginning of an adventure which, to me at least, was in the highest degree novel and interesting.

I ought, perhaps, to premise that the solitary vireo (called also the blue-headed vireo and the blue-headed greenlet) is strictly a bird of the woods. It belongs to a distinctively American family, and is one of five species which are more or less abundant as summer residents in Eastern Massachusetts, being itself in most places the least numerous of the five, and, with the possible exception of the white-eye, the most retiring. My own hunting-grounds happen to be one of its favorite resorts (there is none better in the State, I suspect), so that I am pretty certain of having two or three pairs under my eye every season, within a radius of half a mile. I have

found a number of nests, also, but till this year had never observed any marked peculiarity of the birds as to timidity or fearlessness. Nor do I now imagine that any such strong race peculiarity exists. What I am to describe I suppose to be nothing more than an accidental and unaccountable idiosyncrasy of the particular bird in question. Such freaks of temperament are more or less familiar to all field naturalists, and may be taken as extreme developments of that individuality which seems to be the birthright of every living creature, no matter how humble. At this very moment I recall a white-throated sparrow, overtaken some years ago in an unfrequented road, whose tameness was entirely unusual, and, indeed, little short of ridiculous.

Three or four days after the walk just now mentioned I was again in the same wood, and went past the vireos' nest, paying no attention to it beyond noting that one of the birds, presumed to be the female, was on duty. But the next morning, as I saw her again, it occurred to me to make an experiment. So, quitting the path

suddenly, I walked as rapidly as possible straight up to the nest, a distance of perhaps three rods, giving her no chance to slip off, with the hope of escaping unperceived. The plan worked to a charm, or so I flattered myself. When I came to a standstill my eyes were within a foot or two of hers; in fact, I could get no nearer without running my head against the branch; yet she sat quietly, apparently without a thought of being driven from her post, turning her head this way and that, but making no sound, and showing not the least sign of anything like distress. A mosquito buzzed about my face, and I brushed it off. Still she sat undisturbed. Then I placed my hand against the bottom of the nest. At this she half rose to her feet, craning her neck to see what was going on, but the moment I let go she settled back upon her charge. Surprised and delighted, I had no heart to pursue the matter further, and turned away; declaring to myself that, notwithstanding I had half promised a scientific friend the privilege of "taking" the nest, such a thing should now never be done with my consent.

Before I could betray a confidence like this, I must be a more zealous ornithologist or a more unfeeling man,—or both at once. Science ought to be encouraged, of course, but not to the outraging of honor and common decency.

On the following day, after repeating such amenities as I had previously indulged in, I put forth my hand as if to stroke the bird's plumage; seeing which, she raised her beak threateningly and emitted a very faint deprecatory note, which would have been inaudible at the distance of a few yards. At the same time she opened and shut her bill, not snappishly, but slowly,—a nervous action, simply, it seemed to me.

Twenty-four hours later I called again, and was so favorably received that, besides taking hold of the nest, as before, I brushed her tail feathers softly. Then I put my hand to her head, on which she pecked my finger in an extremely pretty, gentle way,—more like kissing than biting,—and made use of the low murmuring sounds just now spoken of. Her curiosity was plainly wide awake. She stretched her neck to the utmost to look under the nest, getting upon

her feet for the purpose, till I expected every moment to see her slip away; but presently she grew quiet again, and I withdrew, leaving her in possession.

By this time a daily interview had come to be counted upon as a matter of course, by me certainly, and, for aught I know, by the vireo as well. On my next visit I stroked the back of her head, allowed her to nibble the tip of my finger, and was greatly pleased with the matter-of-fact manner in which she captured an insect from the side of the nest, while leaning out to oversee my manœuvres. Finally, on my offering to lay my left hand upon her, she quit her seat, and perched upon a twig, fronting me; and when I put my finger to her bill she flew off. Even now she made no outcry, however, but fell immediately to singing in tones of absolute good-humor, and before I had gone four rods from the tree was back again upon the eggs. Of these, I should have said, there were four,—the regular complement,—all her own. Expert as cow-birds are at running a blockade, it would have puzzled the shrewdest of them to smuggle anything into a nest so sedulously guarded.

Walking homeward, I bethought myself how foolish I had been not to offer my little protégée something to eat. Accordingly, in the morning, before starting out, I filled a small box with leaves from the garden rose-bush, which, as usual, had plenty of plant-lice upon it. Armed in