444 On the Vaso-motor Nei^ves of Striated Muscle. [Dec. 14_, 



striction o£ the artery takes place, which soon reaches its limit, and the 

 hitherto slowly raoving corpuscles remain stationary, the vessel appearing 

 empty, except for a few corpuscles stationed here and there. Upon now 

 stimulating the nerve the vessel is seen steadily to dilate, a slow stream of 

 corpuscles appears in it moving in the reverse direction (that is, from the 

 veins to the artery), and this occurs without the slightest trace of muscu- 

 lar contraction. The dilatation is very appreciable, though not, so far as 

 I have seen, of as great an extent as the stimulus produces when there is 

 a normal blood-stream in the vessel ; and if now the aorta is unclipped, 

 there is at first a slight constriction, followed by a much greater dila- 

 tation. 



At present it appears to me that the pressure in the vein is sufficient 

 to account for this phenomenon ; I intend, however, to carry out further 

 experiments on this point. 



As to reflex stimulation, I have never been able to cause any dilatation 

 in the arteries of the mylohyoid by stimulation of the central ends of 

 either the sciatic or vagus nerves ; but, on the contrary, I have always seen 

 either no effect produced, or a decided though slight constriction of the 

 vessel— slight, that is, in comparison to the marked constriction occurring 

 in the arteries of the web under the same cii'cumstances. 



Loven having noticed the occurrence of dilatation in the saphena 

 artery and in the vessels of the ear of the rabbit upon stimulation of the 

 central end of the tibial nerve and the great auricular respectively, I 

 have attempted to obtain similar dilatation in the web by stimulating the 

 central ends of either the peroneal or posterior tibial nerves, the other 

 nerve in each case being left intaci}, and, in the mylohyoid and pect oralis 

 major muscles, by stimulation of the central end of the opposite mylo- 

 hyoid and brachial nerves Respectively, but in each case have seen no trace 

 of dilatation, but always constriction. 



As to the effect of direct stimulation of the spinal cord upon the vessels 

 of a muscle, I think it probable that dilatation occurs, as Hafiz has as- 

 serted ; but as I have not yet made any systematic experiments to deter- 

 mine this point, I think it best to leave this question for future con- 

 sideration. 



Atropin does not impair the action of the nerve on the vessels of the 

 mylohyoid; for after repeated injections of sulphate of atropin sub- 

 cutaneously, until, with very strong stimulation of the vagus, no effect 

 could be produced on the heart, it was still easy to cause dilatation of 

 the arteries in the muscle by stimulation of the nerve. So, too, large 

 and repeated doses of curare produce no such effect here, as they are said 

 to do on the vagus fibres in the heart. 



As Claude Eernard has described a dilatation of branches of the facial 

 artery and an increase of secretion in the submaxillary gland upon stimu- 

 lation of the mylohyoid nerve in dogs, I have examined other muscles in 

 the frog, and have found that the same phenomena can be produced in 



