The nerves are chiefly the anterior termi nations of those seen in the perineal space. Thus on each side is the inferior pudendal, which leaves the sacral plexus with the small sciatic nerve; while, nearer the median line, are the two superficial perineal nerves (ex ternal and internal perineal). The branches of these are very numerous, and are traceable to the front of the scrotum. The ilio-in guinal, a small branch from the higher part of the lumbar plexus, and which perforates the abdominal niuscles, together with a part of the genito-crural nerve from the same source, terminate near the front of the scrotum, but extend very little on it.
For the anatomy of the contents of the scrotum, as well as its morbid appearances, the reader is referred to the article " TESTICLE," in which they will be included.
(Willianz Brinton.) SECRETION.—This term is usually em ployed to designate the process of separation of those matters from the nutritious fluids of the body, which are destined, not to be directly applied to the nutrition and reno vation of its organised fabric, but (1) to be either at once rernoved as injurious to its welfare, or (2) to be employed for some ul terior purpose in the chemical or physical pro cesses of the economy itself, or to exert some kind of action upon other beings. The term is often used, also, to designate the products thns separated.
The nature of this process of separation is essentially the same in all cases, whatever may be the destination of its products ; and we shall consider it, therefore, in the first place, without any further reference to them, than may suffice to indicate the boundaries of the three groups under which we have ar ranged them. It is probable that in almost every act of secretion a double purpose is served, the blood being freed from some in gredient whose accumulation would be super fluous, if not injurious ; and the fluid sepa rated havincr some secondary- purpose to answer. `Pius, whilst biliary matter becomes a positive poison if it be retained in the blocal, it serves an important purpose, when poured into the duodenum, in completing the diges tive process, and in preparing the nutrient contents of the intestinal canal for absorption. So, again, the cutaneous exhalation not only removes the superfluous water of the blood, but is one of the chief means of regulating the temperature of the body; whilst the sebaceous matter, poured forth by the glandul of the skin, serves to lubricate its surface, at the same time that it relieves the blood of matter which, not beino. nutritive, is extraneous.
Even the urine, which seems to be eliminated merely for the removal of noxious matters from the blood, is sometimes made to serve an additional .purpose, its acridity', or its pe culiarly offensive odour (increased under the influence of terror), frequently rendering it an effectual means of defence. On the other hand, the substances which are separated from the blood for the purpose of discharging some important office in the economy, usually, if not always, contain some substances vt hose retention in the blood would be injurious, and which are therefore advantageously got rid of through this channel. Thus the sa livary, the gastric, and the pancreatic fluids all contain an animal principle nearly allied to albumen ; but this principle seems to be in a state of change, or of incipient decomposition ; and it would seem not improbable, that whilst this very condition renders the albuminous matter useful in promoting the solution of the aliment, it renders it unfit to be retained within the circulating current.
It is impossible, therefore, to divide the secreted products strictly, as some have at tempted to do, into the excrementitious and the recrenzentitious ; that is, into those which are purely excretory in their character, and those which are subservient to further uses in the economy ; most, if not all of them, par taking more or less of both characters. Still we may group the secreting processes for practical purposes, according to the predo• minance of one or other of the objects enu merated above; those being arranged under the first division, in which the depuration of the blood is manifestly the chief end, any other being rendered subservient to this, as is the case pre-eminently with regard to the urine ; those being classed under the second, in which the ulterior purpose of the separated fluid would seem to be the principal occasion of its production ; and this second group being subdivided, according as this ulterior purpose is connected with the operations of the economy itself, as is that of the tears, the saliva, the gastric fluids, &c., or is destined to act upon some other, as is the case with the milk, the odorous secretions, &c.