FUNCTIONAL MECHANISM OF THE SPLEEN. 389 



with or without pigment, etc. The arteries which bring to 

 the organ oxidizing substance soon after entering the organ 

 assume an unusual shape: their outer coat becomes lymphoid, 

 forming nodules similar to the solitary follicles of the intes- 

 tine, i.e., the Malpighian corpuscles, in which lymphocytes 

 are formed. When, after numerous subdivisions, their diam- 

 eter becomes greatly reduced, the arteries resume their normal 

 adventitia and on reaching the pulp in the compartments 

 break up into minute capillaries. The arrangement is, after 

 all, an uncomplicated one, and similar, in general plan, to that 

 of other organs reviewed. 



The connection between the nervous supply of the spleen 

 and that of the other digestive organs becomes evident when 

 the distribution of the coeliac-plexus branches is recalled. 

 "The splenic plexus," say Pick and Howden, 16 "is formed by 

 branches from the cceliac plexus, the left semilunar ganglia, 

 and from the right pneumogastric nerve. It accompanies the 

 splenic artery and its branches to the substance of the spleen, 

 giving off, in its course, filaments to the pancreas (pancreatic 

 plexus) and the left gastro-epiploic plexus, which accompanies 

 the gastro-epiploica sinistra artery along the convex border of 

 the stomach." If we append to this Kolliker's description of 

 the intrinsic nervous supply and the manner in which it is 

 connected with the blood-vessels, it will become apparent that 

 we have a counterpart of the vasculo-nervous mechanism of 

 the stomach, viz.: extensions of the general motor system 

 (sympathetic) and of the vagus, the former being probably 

 represented by the deep net-work in the tunica media, the 

 latter by the oblong meshes of the adventitia. We have here 

 the representatives of the extrinsic supply. 



The functions of the Malpighian corpuscles around the 

 vessels would thus be insured by fibers from the vagus. In- 

 deed, Fusari 17 traced nervous filaments within these bodies. 

 The pulp is also possessed of a "rich maze of fibers consisting 

 of axis-cylinders" doubtless sensory structures. But here an 

 independent motor supply must also be present, since we also 

 have fibers that form "a plexus on the surface of the trabec- 



16 Pick and Howden: "Gray's Anatomy," p. 806. 



"Fusari: Archives Italiennes de Biologie, Turin, vol. xix, p. 288, 1894. 



