Erectile tissue appears sometimes to be de veloped as a morbid production, which has been described under the names of varicose tumour, aneurism by anastomosis, TIMVUS ma ternus, telangiectasis, &c. Its anatomical cha racters are of the same kind as those of the normal erectile tissue; it varies In the, being more or less circumscribed, sometimes sur rounded by a thin fibrous envelope; presenting internally an appearance of cells or spongy cavities, but consisting, in reality, of an in extricable congeries of arteries and veins which communicate by innumerable anastomoses like capillary vessels, but much larger, espe cially the veins. It is difficult to inject it from the arteries, more easy from the neighbouring veins, which are sometimes much enlarged. This alteration most commonly exists in the substance of the skin, where it sometimes re sembles the comb and other analogous parts of the gallinacee. The skin of the face, espe cially that of the lips, is frequently its seat. It has been observed in the subcutaneous cel lular tissue in masses of various dimensions, sometimes so large as to occupy an entire limb. It rarely affects the internal organs; sometimes it extends beneath the mucous membrane of the mouth, mostly in the vicinity of the red borders of the lips. This production is occa sionally affected by a vibratory motion amount ing sometimes to a pulsation resembling that of an aneurismal tumour, which is increased by all the causes which excite the activity of the general circulation ; it cannot be properly said that this structure has the property of under going erection. It is often congenital, some times it appears to have been produced by accidental causes ; it sometimes remains un altered; but it more usually continues to in crease in size until some of its cavities burst, when haemorrhage of a troublesome description ensues.
Beclard considers the limmorrhoidal tumours which occur round the anus as constituting a variety of anormal erectile tissue.
EXCRETION.—This term is applied to the formation of those fluids in the animal economy, which are destined to no useful purpose in the system, but are intended to be discharged from it, and the retention of which is injurious or even Fatal. The term used by the older phy siologists was excrementitious secretions. Some general observations may be made on these ex cretions, with the view both of stating the pre sent extent of our knowledge on this mysterious subject, and of pointing out the importance of an arrangement and combination of facts re lating to it, which are usually treated, perhaps, in too unconnected a manner, but the con nexion of which is already perceptible, and can hardly fail to be satisfactorily elucidated in the progress of physiology.
When we shall have more precise informa tion as to the peculiar, and hitherto obscure principles, which regulate the chemical changes continually taking place in living bodies, it does not seem unreasonable to anticipate, that a dis covery will be made, connecting the excretions of the body with the assimilation of the food, and with the nourishment of the different tex tures, a discovery which may be equally as important in illustrating the chemical phenome na of the living body, as that of the circulation was in explaining those changes which come more immediately under our observation. In
the mean time, we can point out a great deal of contrivance, connected with the general function of excretion, and can state what are the general injurious results, when this contrivance fails of its intended effect; but we are unable to explain how the contrivance effects its purpose, or to point out any general law, by which these in jurious results are determined.
I. We may state, in the first place, that the necessity for some kind of excretion, or dis charge of certain matter from the organized frame, corresponding to the acts of nutrition, or of reception and assimilation of external matter, is a law of vital action, applicable to all organized beings without exception. The uni versality of the excretion of carbon, (whether pure, or in the form of carbonic acid, we need not now inquire,) has been established by the inquiries of Mr. Ellis and others, and the poi sonous influence of the carbonic acid, in an un diluted state, to all living beings, is an equally general fact. In all animals, which possess organs of such size and distinctness as to make their economy matter of observation, other excre tions are likewise observed; and in vegetables, it is not only certain that various excretions, besides the exhalation of water and of carbonic acid, take place, , but it is even believed by De Candolle, that all the peculiar products of vital action, excepting only gum, sugar, starch, and lignine, (which have nearly the same elementary composition, and are convertible into one another,) and, perhaps, fixed oils, are applied to no useful purpose in the economy, and are poisonous to the plants in which they are formed, if taken in by their roots and com bined with their sap; so that, although often long retained in individual portions of the plants, they all possess the essential characters of excretions.* And it appears to be well ascer tained by the observations of De Candolle and of Macaire, that at least great part of the proper juices of vegetables, which descend chiefly by their bark, and are expelled into the soil, are destined to excretion only, and are noxious to plants of the same species, or even of the same Families, if growing in that soil (although often useful to the growth of plants of different fami lies); and this principle has been happily ap plied by the former author to explain the neces sity of rotation of crops of different natural families, to prevent deterioration of the produce.* As this necessity of excrction appears to be so general an accompaniment of the vital action of all organized beings, it seems obvious that there must he some general law, which deter mines the noxious quality of these products of that action, and imposes the necessity of their expulsion. Yet it is certain that the chemi cal elements which pass off in the excretions, are the same which are found in the textures of the animal body, and in the nourishment, whicb is essential to animal life.