772 



SPLEEN. 



of this more will be said hereafter. On an 

 average, its length is from 4 to 5\ inches * ; 

 its thickness from 1 to 1* inches ; and its 

 breadth, from the anterior to the posterior 

 border, 3. to 4 inches. According to Krause, 

 its cubic contents range between 9J and 15 

 inches, with an average of 12. Its absolute 

 weight varies from 6 to 15 oz., according to 

 Soemmering ; from 7^ to 10, according to 

 Krause ; and it has a medium of about 8 oz. 

 According to J. Reid f , between the twentieth 

 and sixtieth years, it ranges from 6 to 10 oz. 

 in the male, and from 3 oz. 13^ dr. to 9 oz. 

 10 dr. in the female. Krause also states, that 

 its specific gravity varies from 1.0579 to 1.0625, 

 with an average of 1.0606. 



The consistence of the spleen is not very 

 great : its parenchyma is soft and doughy, 

 readily yielding to the pressure of the finger. 

 It is not unfrequently torn by mechanical 

 injury during life ; indeed, more easily than 

 any other glandular organ, especially if it be 

 over-distended with blood at the time; but, 

 under the opposite circumstances, it is much 

 less disposed to give way. The colour of the 

 spleen is bluish red, during life greyish violet, 

 and the parenchyma is of a dark dusky red. 



Structure. In the spleen we first distin- 

 guish the coverings or invo/ucra, and the paren- 

 chyma or proper spleen-substance. The first 

 consists of the serous and the fibrous mem- 

 brane. The latter is composed of a frame- 

 work of reticulated fibres firmly connected 

 together, constituting the so-called trabecular 

 tissue (trabeculec Hems') ; and, beside this, of 

 the red spleen-substance, the splenic cor- 

 puscles, and vessels and nerves, together with 

 sheaths which arise from the fibrous coat. 



1. The serous membrane (tunica serosa) is a 

 part of the peritoneum. It accurately covers 

 the outer surface of the spleen as a smooth 

 membrane, with the exception of its hilus 

 only, where it takes the form of two folds 

 which convey the vessels of the organ, con- 

 stituting the gastro-splenic ligament, and pass- 

 ing off to the stomach, where they become 

 continuous with its serous covering. When 

 the ligament uniting the spleen to the dia- 

 phragm exists, the membrane is similarly con- 

 tinuous with the peritoneum covering this 

 muscle. The serous membrane is a thin, mo- 

 derately strong, whitish membrane, which is 

 intimately connected with the fibrous coat ; 

 although in particular places, and especially 

 after previous maceration, the two may be 

 separated from each other. In respect of its 

 microscopical structure, it scarcely differs at all 

 from other parts of the visceral layer of the 

 peritoneum; thus it consists of an outer and 

 single layer of polygonal pavement epithelium, 

 and of an inner layer of white fibrous tissue, 

 in which meshes of fine fibre of yellow tissue 

 are present in no very considerable quantity. 



In mammalia, e. g. in the sheep, ox, &c., 



* In this and the following measurements the 

 German inch and line have been retained, 

 t London and Edinburgh Monthly Journal, April, 



as was remarked by Malpighi, the serous 

 membrane is easily separated entire. But in 

 man this is not the case, and hence Haller 

 and others have supposed that only one 

 membrane is present. But microscopical re- 

 search proves the opinion to be erroneous ; 

 and pathological anatomy confirms this state- 

 ment, by showing that the outer part of the 

 coat of the spleen shares in the diseases of 

 the peritoneum. In animals numerous vessels 

 are seen in the serous membrane, and a very 

 dense network of stronger and thicker fibres 

 of yellow tissue is present. 



2. The fibrous coat (tunica fibrosa, albu- 

 ginea, sive propria) is in man a moderately 

 delicate semi-transparent, but firm, membrane, 

 which encloses the parenchyma of the spleen 

 on every side, so as to include it in a kind of 

 sac. Its outer surface is even, and in man 

 is intimately united with the serous covering, 

 with the single exception of the hilus, where 

 the two membranes diverge, and are separated 

 from each other by vessels, nerves, and a 

 loose areolar tissue. The inner surface bounds 

 the parenchyma of the organ, and, with the 

 exception of very numerous solid processes 

 which come oft' from it, is limited by the tra- 

 becular tissue. At the hilus of the spleen it 

 sinks into the interior of the organ in the 

 shape of tubes (vagincB vasorum), which en- 

 sheath the entering and emerging vessels, and 

 are continued on these throughout the whole 

 parenchyma. The fibrous coat, in the human 

 subject, is composed of white fibrous tissue, 

 mixed with elastic or yellow fibres. The 

 former of these, as in other fibrous membranes, 

 consists of bands, which take a parallel course, 

 but do not form distinct bundles ; and the 

 latter are united in a very dense and irregular 

 network. Duvernoy and Stukely have de- 

 scribed muscular fibres 

 Fig. 522. m this tunic ; but, ac- 



cording to my re- 

 searches, they certainly 

 are not present in the 

 human subject, al- 

 though I have found 

 them existing in some 

 of the mammalia, and 

 most visibly in the dog 

 and pig. They are un- 

 striped muscles, the 

 elements of which, the 

 elongated cells or " fibre 

 cells" (fig. 522.) which 

 I have described *, are 

 deposited in consider- 

 able quantity amongst 

 the elastic network and 

 white fibrous tissue 

 previously mentioned. 

 Muscular fibre-cell from In addition to these 

 the tunica propria of the two animals I have also 

 spleen of the Dog, mag- found the muscular 

 vified 350 diameters. structure j n the ca% the 

 a. nucleus of the same. , . , r^- ' , 



ass, and the Dicotyles 



* Zeitschrift fur wissenschaftliche Zoologie, von 

 v. Siebold und Kolliker, Leipzig, bei Engelmann, 

 Jahrgang, 1848, Heft 1. 



