SPLEEN OF MAMMALIA. 



557 



429 



R5i 





and hindrance to dilatation, prevent any local congestion of blood 

 pressing upon the brain. 



350. Spleen of Mammalia. As with the absorbents, so with 

 the bloodvessels, some change 

 their tubular for a lacunar or 

 cellular form in certain parts, 

 where the blood undergoes, or 

 receives elements of, change ; 

 such parts, resembling ' glands,' 

 are so called, with the qualifying 

 epithets of ( vascular' or 'duct- 

 less.' Of these ( vasoganglions' 

 the chief is the spleen. 



In Mammals this organ is 

 relatively larger than in lower 

 Vertebrates : it is mainly ap- 

 pended to the artery that sup- 

 plies the pancreas, with the left 

 end of which gland it is in 

 close connection, and conse- 

 quently lies to the left or be- 



hind the stomach, to which it is 

 attached by the fold of perito- Venous slmiscs of dura mater) from 1(ellind) Illlllian . 

 neum noted at p. 500. This 



membrane covers the whole spleen, except the ' hilus,' where its 

 two folds support the splenic vessels and form the 43 



f gastro-splenic' ligament. The serous tunic is less 

 intimately adherent to the fibrous or proper capsule 

 in most lower Mammals (Ruminants, e.g.) than in 

 Man ; where the separation only takes place at the 

 hilus. The proper coat consists mainly, and in Man 

 wholly, of white and yellow fibres, the former ar- 

 ranged in bands, the latter in an irregular network. 



^j * *^ 



With these are blended, in some lower Mammals 



(Dog, Pig, e.g.), filamentary fusiform bodies with 



a nucleus, fig. 430, a, called e fibre-cells of un- 



striped muscle' in ccvm". The fibrous tunic is 



reflected into the interior at the hilus, in the form 



of sheaths accompanying the vessels, most complete 



in the human spleen: from the exterior of which Nu , lrarerilanientor 



sheaths, and more abundantly from the inner sur- muscie-i-eii; fr, 



J tunica propna ol 



face of the proper capsule, are sent off white elastic the sl)leL ' 1 ' f -^ 



dog : magnified 3oO 



( trabecular ' bauds, which form a reticular bed for 



