contributing to its enlarged growth. By cutting through both these envelopes with great care, we bring into view a third, of extreme delicacy, very transparent, and of a white colour. This seems to be unconnected with the two envelopes, and no bloodvessels are seen branching through its substance. Immediately within this transparent envelope, which is similar in texture to our own scarf-skin (epidermis) lies the yolk, as yet imperfectly formed; and at the side opposite to that where it was attached to the egg-organ, is placed the rudiment of the future chick (cicatricula). The latter consists of a white bland substance which is not separated by any membrane from the yellow matter of the yolk, but merely lies over it, waiting till the heat imparted in the process of hatching shall develope it so that it may feed upon the yolk supplied for its first nourishment.

This germ, or rudiment of the chick, has no con. nection, M. Dutrochet assures us, with the proper enveloping membrane of the yolk,-a fact which he took great pains to ascertain. He removed the proper membrane of the yolk, which did not exhibit the slightest adhesion to the germ, but left it perfectly entire; and when he examined the membrane thus removed by means of the microscope, he could not perceive the least breach in its substance, nor any difference in its texture or structure. At the point opposite to this, there may be observed, as the egg enlarges, a whitish line or streak, occupying nearly a third of the sphere, which indicates the approaching rupture through which the egg is about to escape from the pouch where it has been confined. In fact, when the egg is separated, the pouch, formed by the two enveloping membranes already mentioned, opens in the direction of this whitish line, and the egg covered by its outer membrane (which is not connected

their pendant beds and procreant cradles; and have been much pleased in observing with what caution the little architect raises a buttress under each shell, before he ventures to form his nest on it."

Some of the less poetical of our northern neighbours, however, it would appear, have a dislike to the window-swallow, and have even gone so far as to endeavour to banish it by preventing it from building. In this vein, we are instructed, by a recent periodical writer, how to discard them. It appears, he says, from experiments made at Granton, that if the places in the corners of windows, and under eaves, where the swallows build, are well rubbed

maining portion, it receives the hard covering of the shell, previous to its exclusion.

New-laid Egg with part of the Shell removed.

It will hence be manifest that, reckoning from the shell inwards, there are six different envelopes, one only of which could be detected before the descent of the egg into the egg-tube. 1. The shell; 2. the external layer of the membrane of the shell; 3. the internal layer; 4. the white; 5. the chalaziferous membrane; 6. the proper membrane.

Harvey was the first who demonstrated two separate whites in an egg, each enveloped in its proper membrane," the one," he tells us, thinner and more liquid, the other thicker and more clammy, and a little more inclining to whiteness,-in staler eggs, after some days' incubation, growing yellowish. As this second white covers the yolk round, so the exterior liquor encompasses it. That these two

selves of so much of these as refer to our present "On the 16th of May," says he, subject. being on a shooting expedition on the top of Pocano mountain, Northampton, when the ice on that and on several successive mornings was more than a quarter of an inch thick, I observed with surprise a pair of these swallows which had taken up their abode on a miserable cabin there. It was about sunrise, the ground was white with hoar-frost, and the male was twittering on the roof by the side of his mate with great sprightliness. The man of the house told me, that a single pair came regularly there every season, and built their nest on a projecting beam under the eaves, about six or seven feet from the ground. At the bottom of the mountain, in a large barn belonging to the tavern there, I counted upwards of twenty nests, all seemingly occupied. In the woods they are never met with; but as you approach a farm they soon catch the eye, cutting their gambols in the air, Scarcely a barn, to which these birds can find access, is without them; and as public feeling is universally in their favour, they are seldom or never disturbed. The proprietor of the barn last mentioned, a German, assured me, that if a man permitted swallows to be shot, his cows would give bloody milk, and also, that no barn where swallows frequented, would ever be struck with lightning.

to build.

"Early in May," continues Wilson, "they begin From the size and structure of the nest, it is nearly a week before it is completely finished. One of these nests, taken on the 21st of June from the rafter to which it was closely attached, is now lying before me. It is in the form of an inverted cone, with a perpendicular section cut off on that side by which it adhered to the wood. At the top, it has an extension of the edge or offset, for the male or female to sit on occasionally, as appeared by the

dung; the upper diameter was about six inches by five, the height externally seven inches. This shell is formed of mud, mixed with fine hay, as plasterers do their mortar with hair, to make it adhere the better; the mud seems to have been placed in regular strata or layers, from side to side; the hollow of this cone (the shell of which is about an inch in thickness) is filled with fine hay, well stuffed in; above that is laid a handful of very large downy geese feathers. Though it is not uncommon for twenty and even thirty pair to build in the same barn, yet every thing seems to be conducted with great order and affection; all seems harmony among them, as if the interest of each were that of all. Several nests are often within a few inches of each other; yet no appearance of discord or quarrelling takes place in this peaceful and affectionate community *"

Aristotle must have meant a different species from either of our mason-swallows, when he remarked that they "rarely build in houses;" for besides this being the locality which ours generally select, we have numerous instances in which the chimney-swallow (H. rustica) both built within houses and also made choice of the most singular parts of houses for its abode. On the authority of Sir John Trevelyan, Bart., we are told by Bewick, that at Camerton Hall, near Bath, a pair built their nest on the upper part of the frame of an old picture over the chimney, coming into the room through a broken pane in one of the windows. They came three years successively, and in all probability would have continued to do so if the room had not been put in repair, which prevented their access to it. Wilson was as much in error as Aristotle when he supposed that this species is distinguished from his barnswallow by never building in barns and outhouses. In Scotland, on the contrary, we have observed that *Wilson, Amer. Ornithology, v. 41.