OEGANS ANNEXED TO TEE ABDOMINAL DIGESTIVE CANAL. 429 



receives the insertion of the great mesentery, by which it is held to the 

 greater curvature of the stomach. The base, or superior extremity, is thick 

 and wide, and responds to the left kidney and the corresponding extremity 

 of the pancreas ; it shows the insertion of the suspensory ligament. The 

 point, or inferior extremity, is smooth and thin. 



Weight. The average weight is 32 ounces ; but it is sometimes of 

 enormous dimensions as much as three or four times its normal volume. 



Mode of attachment, The spleen is a floating organ, whose displacements 

 are limited by a suspensory ligament, and the great (or gastro-splenic) 

 omentum. The first is a peritoneal fold which proceeds from the anterior 

 border of the left kidney and the sublumbar wall, and is strengthened by 

 the elastic fibrous tissue comprised between its two layers. It is fixed to 

 the base of the spleen, and is confounded, inwardly, with the great omentum. 

 The latter is already known as proceeding to the colon, and in its passage 

 becoming attached to the splenic fissure, whence it extends over the sur- 

 face of the organ to form its serous covering. 



STRUCTURE. The tissue of the spleen has a violet-blue colour, sometimes 

 approaching to a red hue ; it is elastic, tenacious, and soft, yields to the 

 pressure of the finger, and retains the imprint. Enveloped externally by the 

 peritoneum, its substance includes a fibrous framework, splenic pulp, Mal- 

 pighian corpuscles, vessels, and nerves. 



Serous membrane. This is developed over the whole surface of the organ, 

 except in the fissure of the anterior border Its internal face adheres most 

 intimately to the proper tunic of the spleen. It is only an expansion of the 

 serous bands which limit the movements of the viscus. 



Fibrous framework. Under the peritoneal membrane is a thick, resisting, 

 fibrous tunic, roughened and granular on its exterior, and sending from its 

 deep face into the interior of the mass a multitude of prolongations called 

 trabeculce, which cross in all directions, forming a cellular network whose 

 numerous narrow meshes contain the other elements of the organ. In 

 washing a morsel of spleen in a jet of water, the latter are removed, and the 

 outlines of this fibrous structure are fully exposed. If a stream of water is 

 passed through, the splenic artery, the same result will be arrived at. 

 Kolliker has found in the proper tunic of the spleen, and in its trabeculae, 

 a particular contractile tissue, the muscular cell-fibres, mixed with fasciculi 

 of elastic or inelastic fibrous tissue. (The proper coat, the sheaths of the 

 vessels, and the trabeculae consist of a dense mesh of white and yellow 

 elastic fibrous tissues, the latter considerably predominating. It is owing to 

 the presence of this tissue that the spleen possesses a considerable amount of 

 elasticity, admirably adapted for the ve.ry great variations in size that it 

 presents under certain circumstances. In some of the mammalia, in 

 addition to the usual constituents of this tunic, are found numerous pale, 

 flattened, spindle-shaped nucleated fibres, like unstriped muscular fibre. 

 It is probably owing to this structure, that the spleen possesses, when acted 

 upon by the galvanic current, faint traces of contractility.) 



Splenic pulp. This name is given to a reddish pultaceous material, 

 which partly occupies the aveolar framework formed by the intersections 

 of the trabeculae. It is sustained by a very delicate reticulum of connective 

 tissue, and is composed of numerous elements, such as pigment granules, 

 free njuclei, large cells with several nuclei, lymphoid elements, and blood- 

 globules in a state of decomposition or transformation. These globules 

 are free or enveloped in an albuminoid membrane. (The proper substance 

 of the spleen consists of coloured and colourless elements. The coloured 



