390 INTERNAL SECRETIONS OF PANCREAS AND SPLEEN. 



ulse," filaments from which penetrate into the trabeculae. 

 These, we have seen, contain much smooth muscle, and the 

 nerve-filaments are connected with them by "swellings" 

 (Fusari), evidently end-plates. Kupffer's bile-alveolus, with 

 its canaliculi, is recalled by a similar receptacle: i.e., Mall's 

 "intralobular venous spaces/' which form the starting-point 

 of the venules that ultimately end in the large trunks leading 

 to the splenic vein. 



If we now trace the process from beginning to end, the 

 functional mechanism appears to us to be as follows: 



The nerve-supply of the spleen is derived from two auton- 

 omous sources: the general motor system (sympathetic) and the 

 vagus system. 



The general motor system supplies efferent nerves, which serve 

 only to maintain tonic contraction of the arteries and of the tra- 

 becular muscles, thus sufficiently activating the flow of blood to 

 the Idbular compartments and to the Malpighian corpuscles to 

 maintain their functional efficiency during the passive period. 



The vagus system supplies both the sensory and motor nerves 

 that excite and govern the functions of the organ during its active 

 period, which begins about the fourth hour of digestion. 



The extrinsic efferent nerves of the spleen, also derived from 

 the general motor and vagus systems, accompany its arterial sup- 

 ply, and jointly constitute its extrinsic constrictor system: i.e., 

 that through which the Hood-flow in the organ is governed. 



The intrinsic efferent nerves are divided into two sets: (1) 

 branches of the general motor system; (2) branches of the vagus 

 system. 



(a) Each branch of the general motor system subdivides into 

 two branches: one of these supplies the middle coat of the arteries 

 and arterioles (the so-called inhibitory nerves); the other is dis- 

 tributed to the muscular elements of the trabeculce. 



(b) The branches of the vagus subdivide in the same manner: 

 one branch supplies the adventitious layer of the arteries, sends 

 offshoots to the Malpighian corpuscles, then passes on to the pulp, 

 where it forms a close net-work; the other forms another plexus on 

 the surface of the trabeculce which inosculates with that of the pulp. 



When the spleen is in the passive state, the general motor 

 nerves alone transmit impulses to all the structures of the organ, 



