576 



(he sensitive spinal nerve-i'taniifioations, met with in the air-bladder. 



The efferent part of (he reflex passes along the Rami intestinales 

 Vagi. This became evident when these two nerves were cut through. 

 It is very probable Ihat (he (eiision and the relaxation of (he sphincter 

 are bronght about b}' different nerves, just as in the case of (he 

 muscles of the bladder of mammals. 



Here. e.g. (he sphincterinieriius is relaxed (tonns-inhibition) along (he 

 nervus pelvicus, whilst (he nerv us hypogas(ricns eifects (he contraction 

 of this muscle. 



What are (he reasons for assuming such an antagonistieinnervalioii 

 also for the duc(us sphincter? The grounds for (his supposition are 

 of two kinds and derived : 1 from experimental data^ 2 from micros- 

 copic observadons. 



1. Experiments. The sphincter is innervaied on both sides by a 

 branch of the Ramus in(cs(inalis Vagi. I have cut (hroiigh this 

 double "innervation in two ways vizi immediately behind (he gill- 

 cover; where the ramus in(estinalis wi(h (he ramus la(eralis bends 

 away from the whole vagus group, and immediaiely near the 

 sphincter (by making a median ven(ral cut). When the vagusbranches 

 had been cut through near the gill-covers, the consequences, as regards 

 the emission of air from the bladder, were the ■ following .- J. the 

 emission was considerably retarded, 2. when air-bubbles Avere emitted 

 the emission no longer took place intermittently, but for a long time 

 at' a stretch. 



Hence we must conclude that (he vagus con(ains inhibitory libres 

 for (he sphinc(er-(onus. 



If (he vagus-branch is cut through immedia(ely near tl)e,spliinc(er 

 the effect is different. The tonus-inhibition is not re(arded, but is no 

 longer intermittent either, and the (onus decreases more and more 

 after the operadon. 



This resuK migh( be explained if it could be demonstrated that 

 the vagus branch near the sphincter also contains fibres for the 

 preservation of the tonus (e.g. sympathetic fibres) the cutting of 

 which caused the tonus to disappear, thus entirely removing the 

 inhibition-delay. 



2. Microscopic observations. What can we gather from the topo- 

 graphic s(udies of Chkvrej, as regards the S3'mpa(he(ic nerve-system 

 of fishes, and our own histological an<l microscopic-ana(oraical resear- 

 ches on sphincierinnervation ? 



Chfa'rkI; divides the sympathetic system of fishes into three parts; 

 the cranial, the abdominal, and (he catidal part. He descrilies (he 

 connection which the ganglia of the first part form with brain and 



