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and lowly Jesus, what can ye mean, when we hear you prate about your Church being the most tolerant church in christendom. Tolerant, indeed; then what does the incarcerationthe long and wearisome incarceration-of John Thorogood mean? He believes your system to be unscriptural, your altars to be polluted, and his conscience tells him he must not be actively concurrent in their support. Admit that he may be wrong in this, still such are his convictions, and as an honest man he acts accordingly. This is his only crime, and how do ye meet it? Shame upon ye, Protestants ! lasting, burning shame! Discard the name ye bear, or open the doors of his prison-house, and let the captive go free. The very papists hiss, and smile contemptuously upon you. Rome invites you to her boson, and hopes to find in your rampant bigotry materials more fitted to her purpose than her own communion supplies.
The claims of John Thorogood on the friends of religious liberty cannot be overrated. This is simple truth, and it is due to the victim of priestly intolerance to state it. If those claims have been neglected in any quarter, whence sympathy and kind feeling were especially to be expected and we confess our suspicions that such has been the case-yet the future may remedy in good part the past, and teach our enemies that whatever oversights have been committed, and temporary misunderstandings have arisen, we are nevertheless one in heart and purpose. To have neglected a duty is bad, to persist in and to justify such neglect is tenfold worse.
Art. VI. Guy's Hospital Reports. Edited by GEORGE H. BARLOW,
M.A. and L.M., Trin. Coll. Cam., and JAMES P. BABINGTON, M.A., Trin. Coll. Cam. October, 1839. Art. Mr, Towne's Observations on the Incubated Egg. London : Highley,
A GROWING interest in scientific researches is one of the
features of the present times. The knowledge which is accumulated from this source is no longer the exclusive property of a profession. Chemistry, so replete with wonders, is cultivated by others beside the medical profession. Her opulent treasures, while collaterally they multiply the agencies of the healing art, are the source of wealth to the merchant, of fascination to the studious inquirer, and of numerous delights to society at large. The kindred sciences of anatomy and physiology present attractions also to the general reader. The cumbrous and forbidding phraseology which surrounds them affords but a feeble barrier against intruders, and
when carried into the wider department of inquiry which the animal kingdom supplies, the phenomena they reveal constitute an assemblage of designs, illustrating the adaptation of means to ends, and emphatically announcing the power, wisdom, and beneficence of the Creator. It is here the contemplative mind delights to repose. Avoiding the mazes of speculation, it enters a world of realities, every one of which bears the impress of the divine hand; and amidst the scene of wonders which are unveiled, none would be more amazing, than that the investigator himself should return with his mind unawed, unrefined, unimproved.
To watch the development of the chick under incubation has long been a favorite pursuit among scientific naturalists; and an array of eminent men, during a long series of years, might be cited as having lent their talents to elucidate the process. The subject, indeed, is inviting. It is the only means, within reach, where the formative process can accurately be noticed, and from the don stic habits of the hen, and the facility with which eggs can be procured, experiments may be repeated and conclusions tested, without restriction. It is, too, free from the revolting method of injuring the mother, while it embraces all that can be desired for close, extended, and conclusive observation. We had, indeed, reason to believe that the field had already been well-troddenthat the structures, harmonious actions, and relations of this beautiful microcosm had been displayed, and that only occasional and isolated additions were left for future investigators. It appears, however, that in this we have been deceived, for our attention has been directed to some observations by Mr. Towne, of Guy's Hospital, in which the author propounds several opinions utterly at variance with those ordinarily entertained on the subject.
It would be foreign to our purpose, and incompatible with our limits, minutely to describe the various changes which attend the evolution of the chick. An account of them, with illustrative engravings, may be seen in the fourth volume of Sir Everard Home's works, or as copied from him, in a much more accessible form, in the volume on the Domestic Habits of Birds, published in the Library of Entertaining Knowledge. Our object at present will be just so far to sketch the process as to render it intelligible to our readers; and by condensing the results of previous experimenters and reviewing the observations of Mr. Towne, impartially to seek out the truth.
The time required for the complete formation of the chick is twenty-one days. Commencing as a small spherical speck on the surface of the yolk, it gradually enlarges, and variations are appreciable on each successive day. The yolk, being specifically lighter than the white or albumen, has a tendency to rise to the part which is uppermost, whilst by some small ligamentous bands termed the chalazes or poles, it is permitted to revolve on its
axis, and its motion upwards is restrained within certain defined limits. We shall have occasion to recur to this mechanism so admirably adapted to secure that position of the germ which is most favorable for its receiving the nutrient warmth of the mother, at the same time preventing its tender structures from being bruised by rough contact with the shell or lining membranes. The form of the cicatricula, or rudiment of the future chick, changes from a spherical to a more longitudinal shape, and the progress of its organization is seen by a blood vessel coming out from either side of it, branching into numerous smaller vessels, which unite at their termination, forming a marginal boundary on the covering of the yolk. The chick is the centre of this network of vessels, and as the embryo increases so do these vessels multiply, covering daily a larger space until they nearly per. vade the membrane of the yolk. It appears from a beautiful experiment of Mr. Towne's, that at the first formation of these vessels, and probably before them, each branch is accompanied by a vessel carrying yolk into the body of the chick, which no doubt supplies the pabulum for its sustenance and growth. Between the third and fourth day a remarkable change is visible in the contents of the shell. The yolk suddenly becomes flattened, and a portion of the white or albumen is found to have penetrated the yolk bag. At about the same period a vascular membrane, termed by Sir E. Home, the vesicle, has so far become developed as to have passed from the body of the chick to the lining membrane of the shell. The increase of this membrane is proportioned to the growth of the embryo. It continues to enlarge over the surface of the membrane of the shell, which towards the end of incubation it entirely surrounds, thus forming an external covering to the yolk. This vesicle, or chorion, is full of bloodvessels-a system of arteries and veins—carrying livid red blood from the body of the chick, and returning it a bright red colour, fitted for the elimination of the structures of the chick. If an egg be opened between the twelfth and thirteenth day of incubation, this membrane will be prominently apparent; the pulses of the numerous blood-vessels will be seen propelling their contents, and presenting to the eye of the observer so animating and interesting a sight as to have been declared by Blumenbach to be the most beautiful spectacle in the organic creation. The progressive evolution of the chick is evinced by the development of its several organs. At about the sixth day its bare wings and legs are fully seen; the eyes are large and prominent, the brain and bill are clearly distinguished, and its organization is going on to completion. A few days additional growth discovers the wings and body covered with short feathers; and that which a week or ten days before was but an amorphous mass, is now furnished with shape, proportion, and organic life. About the fifteenth
day the yolk-bag begins to be taken up into the abdomen of the chick. The albumen has now disappeared from admixture with the yolk, and in this state, towards the completion of the chick's residence in the shell, it is found to have been gradually received into the chick's abdomen. We may here mention, that there is a small reservoir of air, called the folliculus aeris, enclosed between two membranes at the larger end of the shell, which increases in the progress of incubation. At the nineteenth day the vocal organs come into play, consequently respiration is established; the large blood-vessels which connect the chick with the chorion—any one of which if left open would prove fatal to the embryo—begin to be sealed and shrink, and every thing is combining to aid the chick in breaking its shell, and emerging into independent existence. The preparations necessary for completing this purpose are very remarkable. The package of the ehiek is so arranged, that while the body and appendages are enclosed in the smallest possible space, there is yet a passage left free in the long axis of the chick's head, to allow sufficient impetus to be gained by the recession of the head and neck, as to collect force enough by repeated blows, to break the shell and make its escape. The head itself is confined between the hip on one side and the wing on the other, which passes over the head as represented by Mr. Towne, in just contradiction of Sir E. Home's engraving. By this means anv lateral movement of the head is prevented, and the instinctive b.ows of the chick are directed to one spot, and not diffused and enfeebled as would be the result were its power of motion in this direction unrestrained. The tip of the upper mandible is supplied with a thick, hardened, horny point expressly for the purpose of breaking the shell, as it drops off after the chick has gained its liberty.
In preparing, at the request of the Treasurer of Guy's Hospital, a series of models to illustrate the changes in the hen's egg during incubation, Mr. Towne thought he had little else to do than to fix on some standard work, say Sir Everard Home's, and follow the author; or, as Mr. T. expresses it, “place myself under his (Sir • E. Home's) guidance, follow his track, and arrive at his results. • I soon found (adds Mr. T.) that either I must consent implicitly to adopt the opinions of others, or determine to look and judge
for myself.' And the results of this unshackled investigation are embodied in the
paper which we now propose to consider. We find that the first position, in the order of his observations that Mr. Towne has attacked, is the prevailing theory of the decarbonization of the blood. The chorion, as we have mentioned, is developed immediately beneath the lining membranes of the shell, in order, as was universally supposed, that the blood should be decarbonized by the air penetrating the porous shell, and that the folliculus aeris was a provisionary arrangement for the inter
val of time before the chorion had sufficiently grown. This theory has had the sanction of time, authority, analogy, concurrent testimony, and the confirmation of experiment. Mr. Towne first entertained a doubt of the correctness of the theory from observing that the lining membrane of the shell became uniformly thicker as incubation advanced, thus opposing a greater obstacle to the accession of air to the chorion, where it was evidently most needed. Frequent observation placed this fact beyond doubt, which Mr. Towne, with praiseworthy zeal, ascertained to exist also in the eggs of the linnet, sparrow, blackbird, moorhen, partridge, turkey, duck, and goose. The experiment on which the theory rested was, that the death of the chick followed on rendering the shell impervious to air by a coat of varnish.
• Now it seemed to me (says Mr. T.), that unless a perfectly innocent varnish had been employed, this was not a satisfactory experiment, inasmuch as admitting the shell to be pervious to air, so would it certainly be to any smell which might attach to a substance thus employed. I then determined to repeat the experiment in my own way.'
The experiment consisted in varnishing a number of fresh eggs with successive coats of thickened albumen, until the shells were
completely lackered. They were then enveloped with four coverings of paper cut like the sections of an orange, well soaked in albumen, and so critically adjusted as to bring the middle of each section opposite the joining in the previous coating.? “The whole formed a covering so thick and horny that I felt convinced it was entirely impermeable.' These eggs were submitted to incubation on the 18th of April, and one of them was opened on each day between the 4th and 10th inclusive, and the chicks had gone through all their changes without interruption.' The venous and arterial circulation was beautifully seen at the eleventh and twelve and a half days, under the same circumstances, and one egg that was opened on the nineteenth day, exhibited a proportionate maturity. No process had been suspended, and the chick was living and vigorous, and evinced a strong disposition to make its escape from the shell.' Mr.
Towne, sensible of the extreme importance of disturbing the prevailing opinion on insufficient evidence, submitted it to å still more rigorous test, adding an extra coat of paper to the four in the other experiment, and then three coats of oil-paint composed of white-lead, with a large portion of sugar of lead as a
drier ; this I did with the double intention of offering an additional obstruction to the air, and also to prove whether the 'paper was or was not entirely sufficient for the purpose : con