Volume 1

A history of the earth, and animated nature / By Oliver Goldsmith. With an introductory view of the animal kingdom, tr. from the French by Baron Cuvier. And copious notes embracing accounts of new discoveries in natural history: And a life of the author by Washington Irving. And a carefully prepared index to the whole work.

  • Oliver Goldsmith
Date:
1847
Catalogue details

Licence: Public Domain Mark

Credit: A history of the earth, and animated nature / By Oliver Goldsmith. With an introductory view of the animal kingdom, tr. from the French by Baron Cuvier. And copious notes embracing accounts of new discoveries in natural history: And a life of the author by Washington Irving. And a carefully prepared index to the whole work. Source: Wellcome Collection.

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    tory organs, which will be more fully explained hereafter. In the first, or tadpole state, the organs are branchial, in the frog they are pulmonary. The arrangements are striking and singular. All respiration must be either aquatic or atmospheric. In the former case, the respiration is said to be cutaneous or branchial, according as it is performed through the skin or through gills. On the other hand, atmospheric respiration may be either tracheal or 'pulmonary, according as it is per- formed through the air-tubes called trachece, or by means of lungs. After the blood has been purified by respiration, it is fitted to restore the com- position of all parts of the body, and to execute the function of nutrition properly so called. The wonderful property, possessed by the blood, of decomposing itself so as to leave precisely, at each point, those particular kinds of particles which are there most wanted, constitutes the mysterious essence of vegetative life. We lose all traces of the secret process by which the restoration of the solids is performed, after having arrived at the ramified extremities of the arterial canals. But in the preparation of fluids we are able to trace appropriate organs, at once varied and complicated. Some- times the minute extremities of the vessels are simply distributed over extended sur- faces, from which the liquid exudes; and sometimes the liquid runs from the bottom of minute cavities. But the more general arrangement is, that the extremities of the arteries, before changing into veins, form particular vessels called capillary, which produce the requisite fluid at the exact point of union between these two kinds of vessels. The blood-vessels, by interlacing with the capillary vessels which Ave have just described, form certain bodies called conglomerate ox secretor-y glands. With all animals destitute of a circulation, and especially with insects, the nutritive fluid bathes the solid parts of the body; and each of them imbibes those particles necessary for its sustenance. If it become requisite that any particular fluid should be secreted, capillary vessels, adapted for this purpose, and floating in the nutritive fluid, imbibe, through their pores, the elements necessary for the composition of the fluid to be secreted. It is thus that the blood continually renovates all the component parts of the body, and repairs the incessant loss of its particles, resulting necessarily from the continued exercise of the vital functions. The general idea which we are able to form of this process is sufficiently distinct, although the details of the operations performed at each particular point are involved in obscurity, from our ignorance of the precise chemical composition of each part, and our consequent inability to deter- mine the exact conditions necessary for their reproduction. In addition to the secretory glands necessary for performing a part in the internal economy of the system [such as the liver and the pancreas], there are others Avhich secrete fluids destined to be rejected, either as being superfluous, or for some purpose useful to the animal. Of the latter Ave may mention the black fluid secreted by the Cuttle fish [Avith Avhich, when pursued, he obscures the water to cover his retreat], and the purple matter of several Mollusca. The function of generation is involved in much greater obscurity and difficulty than that of simple secretion; and this difficulty attaches chiefly to the production of the germ. We have already explained the insuperable difficulties attending the pre-existence of germs; yet, if once Ave assume their existence, no particular difficulty remains attached to generation [Avhich is not equally applicable to ordinary secre- tion]. While the germ adheres to the mother, it is nourished as if it formed a jAart of her OAvn body; but Avhen the germ detaches itself, it possesses a distinct life of its oAvn, essentially similar to that of an adult animal. The form of the germ, in its passage through the several progressive states of development, successively termed the embryo, the foetus, and, finally, the neAv-born [ animal, never exactly resembles that of the parent; and the difference is often so very great that the change has received the name of metamorphosis. Thus, no person could ever anticipate that the caterpillar Avould finally be transformed into the but- terfly, until he had either observed or been informed of the fact These remarkable changes are not peculiar to insects, for all living beings are ■ more or less metamorphosed during the period of their groAvth; that is to say, they j lose certain parts altogether, and develop others Avhich Avere formerly less consider- | abla Thus, the antenna;, tlie Avings, and all the parts of the butterfly, Avere concealed !