1. Defect And Excess Of Formation

The spleen is generally absent in acephalous monsters, together with other organs of the abdomen and thorax. Occasionally it is found wanting, together with the stomach or the fundus of the stomach, in subjects that are otherwise well developed, or it exists in a rudimentary state, whilst the stomach is in a normal condition. The explanation of these phenomena is to be sought in the history of the development of the embryo.

The spleen is found double in biventral monstrosities. The multiplication of the spleen, in the shape of lienes succenturiati, is not to be viewed as an increase, but as a subdivision of the organ, which does not affect its individuality. We not unfrequently find, besides the main organ, small accessory spleens (lienes succenturiati) seated in the omentum and ligamentum gastrolienale. They vary in size from that of a millet-seed to that of a walnut, and in number from one to twenty. They are round, present the same structure as the spleen, and are morbidly affected at the same time, and in a similar manner as the latter. The marginal indentations of the spleen, or the complete separation of a portion of the organ by a horizontal fissure, form transitions to this abnormal condition.

2. Deviations Of Size

Deviations of size consist either in an abnormal increase or diminution of the organ. The former is of particular importance, and those tumors afford a special interest, which depend upon congestion caused not by mechanical impediments, but by the peculiar relation of a morbid state of the blood to the spleen. With the rare exceptions of those cases in which, like analogous states of the liver, they are congenital, these conditions are acquired. They are either acute or chronic: in the former case they accompany other acute diseases, either during their entire course, or only during single stages; in the latter, the tumefaction results from dyscrasiae or cachectic conditions, which induce congestion, induration, and hypertrophy of the spleen. These terms, however, from referring mainly to external appearances, are apt to cause the real nature of the disease to be overlooked.

It is unnecessary to enter more fully into the consideration of these changes affecting the splenic parenchyma, which are evidenced by tumefaction, as it will be more appropriate to treat the subject under the head of Textural Diseases. We merely add the following remarks: a. Acute tumefaction is generally accompanied by considerable softening of the splenic parenchyma; chronic tumefaction by increase in the consistency of the organ. It is questionable whether the hypertrophy affects the elementary tissue and constitution of the spleen: this is a point which requires to be elucidated by further research; but there is no doubt of the fibrous trabecule of the spleen and its fibrous capsule becoming hypertrophied in old chronic tumors. When we have succeeded in reducing an acute or chronic tumor, or even a mere hyperaemic state of the spleen, we often find the sheath of the spleen thickened, opaque, corrugated, and relaxed after death - a fact which may serve as a useful indication.

b. The size attained by chronic tumors of the spleen is often very considerable. The spleen not unfrequently measures sixteen inches in its long, seven inches in its short diameter, and four inches in thickness; its weight may amount to thirteen pounds and a quarter, and, according to the observations of others, even to twenty and more pounds.

Diminution of the spleen is characterized by shrivelling of the fibrous tissue, -which prevents the vessels from being injected; and is peculiar to genuine cholera (cholera algida), or it occurs as atrophy, in consequence of a special change in the fluids at large. Under this head we must class numerous obscure cases of permanent diminution of the spleen in individuals who in no way resemble each other, of the reduction of the spleen observed by some pathologists as resulting from the use of steel, and of the senile involution of the spleen.

Atrophy varies in degree; it occasionally advances to such an extent during the involution of the organ, as to reduce it to the size of a hen's egg or walnut.

The spleen in these cases is paler than usual, its consistency is increased or diminished, the organ may assume the toughness of leather, or become soft, friable, and pultaceous. Senile atrophy may be characterized in the following manner: the spleen is considerably reduced in size, and flabby; its sheath is opaque, corrugated and thickened, but at the same time softened and easily ruptured; the parenchyma consists of a pulp which is of the color of rust or the lees of wine, and which is enclosed in dense and equally friable, fibrous tissue. We not unfrequently find the sheath of the spleen indurated and cartilaginous, or ossified, and at the same time, ossification of the arterial ramifications and free calcareous concretions (phlebolithes) in the veins of the organ.

3. Deviations Of Form

We not unfrequently meet with a tongue-or platter-shaped, almost cylindrical, globular, or angular spleen; its edges may be more or less notched, which is particularly the case with the anterior margin; and the indentation may extend so far as to cause a transverse division of the organ. These furrows are not to be confounded with the contractions that are occasionally produced by inflammation and metastasis, and which very much resemble the former.

4. Deviations Of Position

The congenital anomalies that come under this head consist in the spleen occupying a place external to the abdominal cavity, when the latter is fissured, in its being placed in large umbilical herniae, and in the left thoracic cavity when the diaphragm is absent, and in a varying position, consequent upon an anomalous congenital elongation of the peritoneal attachments.

Acquired deviations of position consist in a descent of the spleen, when forced down by enlargement of the left side of the thorax, or in its being pushed up by dropsical and ascitic accumulations, or by a tympanitic state of the intestine; in its dislocation by various turners, or in its descent from increase in size and weight. Enlarged spleens sink vertically into the left mesogastric region, or raise the diaphragm, or they descend to the ileum, and in the case of a still further increase of size, slide off from the latter, so as to occupy a diagonal position in the hy-pogastrium, and extend over the right ileum. There is no doubt that the spleen occasionally presents very loose attachments, and remains freely movable, even after it has been reduced from a hypertrophied state to its normal size, in consequence of the previous traction exerted upon its ligaments.

5. Solutions Of Continuity

Under this head we class injuries of the spleen inflicted by cutting instruments, rupture consequent upon blows or knocks received in the region of the spleen, contusions, as in being run over, concussions, as in a fall, and spontaneous ruptures. The latter are of peculiar interest, as they are the result of acute and violent tumefaction of the organ, proceeding to a most intense degree. We are able to confirm the fact observed by other authors, of the occurrence of spontaneous rupture in typhus, in typhoid cholera, and in the hot stage of ague, and the consequent fatal termination from hemorrhage.

6. Diseases Of Texture

The chief diseases that appertain to this class, the hyperaemiae, the so-called infarction and hypertrophy, and inflammation of the spleen, require, in order to be duly appreciated, not only anatomical proof of the existence of the disease, based upon a clear notion of the structure of the organ, but more especially an advance in our knowledge of the pathology of the blood and the serum. Numerous diseases, and more particularly the simplest derangements, as many cases of hyperaemia, can only be elucidated by attending to these points. These diseases of the spleen are probably but rarely idiopathic; they almost always arise from certain anomalies of the blood and the serum, or from certain dyscrasise, which, though little known, and as little understood, bear a remarkable and positive relation to the spleen. The spleen may in fact be considered as the most sensitive test for a variety of dyscrasic states of the fluids. An acquaintance with this connection may serve to lift the veil which still conceals the true function of this organ. We shall now resume the consideration of tumefaction of the spleen, upon the basis of the above remarks, and enter into a more minute investigation of the subject than we could adopt in the previous general outline. The main points relating to deviations of consistency will at the same time be adverted to.