884 THE SPLEEN. 



slightly notched, especially towards the lower part. The lower end is pointed, 

 and is in contact with the left end of the arch of the colon, or with the 

 transverse ineso-colon. The position of the hilus corresponds with the line 

 of attachment of the gastro-spleuic omentuin. Along the bottom of this 

 fissure are large openings or depressions, which transmit blood-vessels, with 

 lymphatics and nerves, to and from the interior of the organ. In some 

 cases there is no distinct fissure, but merely a row of openings for the 

 vessels ; and in others the situation of the hilus is occupied by a longitu- 

 dinal ridge, interrupted by the vascular orifices. The peritoneal connections 

 of the spleen have been already described (pp. 827 and 830). A portion 

 of variable extent behind the hilus, and towards its lower end, will usually 

 be observed deriving its peritoneal covering from the sac of the omentum. 



The spleen varies in magnitude more than any other organ in the body ; and this 

 not only in different subjects, but in the same individual, under different conditions, 

 sometimes appearing shrunk, and at others being much distended. On this account 

 it is difficult or impossible to state what are its ordinary weight and dimensions: in 

 the adult it measures generally about 6 or 5\ inches from the upper to the lower end, 

 3 or 4 inches from the anterior to the posterior border, and 1 or 1J inch from its 

 external to its internal surface ; and its usual volume, according to Krause, is from 9| 

 to 15 cubic inches. In the greater number of a series of cases examined by Eeid, its 

 weight ranged from 5 to 7 oz. in the male, and was somewhat less in the female ; but 

 even when perfectly free from disease, it may fluctuate between 4 and 10 ounces. Gray 

 states that the proportion of the spleen to the weight of the adult body varies from 

 1 : 320 to 1 : 400. In the foetus the proportion is as 1 : 350. After the age of forty the 

 average weight gradually diminishes, so that in old age the weight of the spleen is to 

 that of the body as 1 : 700 (H. Gray). The specific gravity of this organ, according to 

 Haller, Scemmerring, and Krause, is about 1'060. In intermittent and some other 

 fevers the spleen is much distended and enlarged, reaching below the ribs, and often 

 weighing as much as 1 8 or 20 Ibs. In enlargement and solidification it has been 

 known to weigh upwards of 40 Ibs. ; and it has been found reduced by atrophy to the 

 weight of two drachms. 



Small detached roundish nodules are occasionally f und in the neighbourhood of 

 the spleen, similar to it in substance. These are commonly named accessory or 

 supplementary spleens (splenculi ; lienculi). Of these 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, varying from 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, and also the 

 deeper notching of the anterior margin of the organ which sometimes occurs in man. 



Structure. The spleen has two membranous investments a serous coat 

 derived from the peritoneum, and a special albugiueous fibre-elastic tunic. 

 The substance of the organ, which is very soft aud easily lacerated, is of a 

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

 the 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 frame- 

 work of whitish elastic bands or trabcculce, of an immense proportion of 

 blood-vessels, the larger of which run in elastic canals, and of a peculiar 

 intervening pulpy substance, besides lymphatic vessels and nerves. 



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

 tunic beneath, but it may be detached by careful dissection, commencing at 

 the borders of the hilus. 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 proper tunic, much thicker and stronger than the serous, is whitish in 



