The morbid appearances of the larynx resemble those of the rest of the windpipe, being chiefly ossification of its cartilages, and inflammation or ulceration of its mem branes or muscles.
Various morbid appearances have been observed in the thyroid gland. It is sometimes scirrhous and ra ther enlarged, and it has been seen in a state of ossifica tion. In a few cases it is affected with common inflam mation ; but the morbid appearance most frequent in the thyroid gland, especially in some particular countries and districts, is that peculiar swelling which forms the characteristic of the disease called bronc/zocele or goitre, so common among the peasants of Savoy. It is then seen of a cellular texture, and containing a transparent viscid fluid.
On the structure of organs of respiration and voice, Sce Winslow's Traite d'Anatomie; Portal's Anatomic Medicate; Dumas' Principes de Physiologic, tome iii. ; Bichat's Anatomic Descriptive, tomes ii. and iv. ; Bell's Anatomy, vol. xiy. ; and Fyfe's Compendium of ,lnatorny, vol. ii.
Of the ORGANS of SECRETION and EXCRETION.
Ix the course of this article we have repeatedly had occasion to notice several of those organs which either mediately or immediately separate from the ge neral mass of blood ; those fluids that either answer some useful purposes in the animal economy, or which are destined to be thrown from the system as excremen titious. These are the organs of secretion and excretion. In general, the organs of secretion separate the useful fluids, while those of excretion separate or prepare those which may be considered as excrementitious. This general notion of the secretory and excretory or gans must not, however, be carried to far ; for, as our knowledge of the animal economy is not so complete as to enable us to decide, with certainty, what fluids are beneficial, and what injurious or excrementitious, we cannot with certainty decide how tar sonic of the organs belong exclusively to the one function or the other, or whether sonic of them may not be considered as belong ing to both.
The organs of secretion and excretion, d lifer consider ably from each other, with respect to the simplicity of their structure. Some of them appear only to separate from the blood matters that arc already formed in that fluid ; such are the serous membranes that line the close cavities of the body, and perhaps the cellular membrane that forms the general connecting medium of the whole structure. These are the simplest in their organization,
consisting of little more than secreting surfaces, provi ded with exhalant vessels. A second class separate from the blood certain fluids, which, though not exactly the same as what are found in the blood, have undergone very little change. To this class belong the synovial membranes that are attached to the articulations of the hones, and the mucous membranes that line what may be called the open cavities of the body. The harmer of these differ little, either in structure or immediate function, from the serous membranes ; hut the latter are both more complex in their organization, as having attached to them an apparatus of glands resembling those of the next class ; and they are more important in their functions. The third class consists of those organs which completely alter the fluids that circulate through them, and prepare platters that either arc not found at all within the blood-vessels, or are contained there in very different proportions. To this class belong the nu merous glandular bodies, such as the liver, the kidneys, the testes, the breasts in women, &c.
If these general remarks be correct, we may arrange the principal secreting and excreting organs under a comprehensive view, as in the follow ing table.
Of Secreting Membranes.
We have already given an account of two of the ge ,nerai secreting membranes, viz. the cellular membrane, in the introduction to this part of our article, and of the synovi tl membranes in Chap. I. when treating of the joints. We have also briefly described several of the serous and mucous membranes, as connected with the cavities that have been considered in the preceding chapters; hut we shall here give a general view of the serous and mucous membranes, considered as two of those important textures that enter into the composi tion of the animal body. In this view we shall follow the Anatomic. Generale of Bichat, as almost the only work that contains a systematic and general account of these component textures. We shall, however, so far depart from his arrangement as to consider the serous mem branes before the mucous, conceiving the former as the more simple in their structure and functions.