CHAP. IIL] ELIMINATION OF WASTE PRODUCTS. 713 



and by experiments on animals we learn that stimulation of either 

 the one or the other set produces contractions of the bladder ; and 

 further experiments have shewn the paths taken by the motor 

 impulses in each case. We may infer that in ourselves the im- 

 pulses bringing about micturition take similar paths, allowances 



>PI,hyp 



FIG. 90*. DIAGRAM TO ILLUSTRATE NERVOUS MECHANISM OF BLADDER IN THE CAT. 



SI, Bladder. Sy, Sympathetic chain, r.c, rami-communicantes of lumbar 

 nerves II. to V. G.m.i, Inferior mesenteric ganglion, surrounding A the inferior 

 mesenteric artery. Hyp, Hypogastric nerve, that on the right-hand side being cut 

 through, n.e, nervi 'erigentes, branches from S the sacral nerves I to III and from 

 C.I, first coccygeal nerve. Pl.hyp, Hypogastric plexus, y, branch of plexus 

 carrying fibres from nervi erigentes to bladder, g, small collections of nerve-cells 

 in hypogastric plexus, a, branches of plexus cut across. 



The dotted lines belonging to L.II, L.V, S.I, C.I shew that these are infrequent 

 or uncertain paths of the nervous impulses to the bladder. 



F. ii. 46 



