398 THE SPLEEN-. 



1"060. In intermittent and some other fevers the spleen is much enlarged, 

 reaching below the ribs, and often weighing as much as 18 or 20 lbs. In 

 enlargement and solidification it has been kno^wn to weigh upwards of 40 lbs ; 

 and it has been found reduced by atrophy to the weight of two drachms. 



Small detached roundish nodules are occasionally found in the neighboui-hood 

 of the spleen, similar to it in substance. These are commonly named acccswri/ 

 or svjJj^lt'mcntary spleens (splenculi ; lienculi). One or two most commonly 

 occur, but a greater number, and even up to twenty-three, have been met with. 

 They are small rounded masses, varjing fi-om the size of a pea to that of a 

 walnut. They are usually situated near the lower end of the spleen, either in 

 the gastro-splenic omentum, or in the great omentum. These separate splenculi 

 in the human subject bring to mind the multiple condition of the spleen in 

 some animals ; as does also the deei^er notching of the anterior margin of the 

 organ which sometimes occui's in man. 



STRUCTUEE OF THE SPLEEN. 



The spleen has two membranous investments — a serous coat derived 

 from the peritoneum, and a special albuginous fibro-elastic tunic. The 

 substauce of the organ, which is very soft and easily lacerated, is of a 

 dark reddish-brown colour, but acquires a bright red hue on exposure 

 to tlie air. Sometimes, however, the substance of the spleen is paler, 

 and has a greyish aspect. It also varies in density, being occasionally 

 rather solid, though friable. The substance of the organ consists of a 

 reticular framework of whitish elastic bands or imheculcc, of a large 

 proportion of blood-vessels, and of a peculiar intervening pulpy sub- 

 stance, besides nerves and lymphatic vessels. 



The serous coat is thin, smooth, and firmly adherent to the elastic 

 tunic beneath. It closely invests the surface of the organ, except at 

 the places of its reflection to the stomach and diaphragm, and at the 

 hilus. 



The t-unica, propria (284, a), much thicker and stronger than the 

 serous coat, is Avhitish in colour and highly elastic. It is continuous 

 with the trabecular structure within. Along the hilus this coat is 

 reflected into the interior of the spleen, in the form of large trabecute, 

 supported and enclosed by which run the blood-vessels and nerves; so 

 that these are, as it were, ensheathed by prolongations of the fibrous 

 coat. These sheaths ramify with the vessels which they include, as 

 far as their finer subdivisions, and are connected with the numerous 

 trabecular processes Avhich pass into the interior from the whole inner 

 surface of the fibrous coat. The arrangement of the sheaths and 

 trabecule may be easily displayed in the spleen of the ox by pressing 

 and washing out the pulp from a section ; and then they are seen to 

 form a close reticulation through the substance. Thus, the proper coat, 

 the sheaths of the vessels, and the trabecula3, all of a highly elastic 

 nature, constitute a distensible framework, which contains in its inter- 

 stices or areolas the vessels and the red pulpy substance of the spleen. 

 These fibrous structures are composed of interlaced bundles of areolar 

 tissue containing a large amount of fine elastic tissue. In addition to 

 these elements, in the spleen of the pig, the dog, and the cat, and to a 

 smaller extent in that of the ox and sheep, there is found an abundant 

 admixture of plain muscular fibre-cells, resembling those of the middle 

 coat of arteries, A scanty admixture of similar fibres occurs also 

 in the trabecule and fibrous coat of the human spleen (Meissner, 

 W. MuUer). The elasticity of the fibrous coat and trabeculas, together 



