218 BIOLOGY. [BOOK. n. 



great cervical sympathetic nerve we have sectionised, we provoke 

 the redness of the ocular conjunctiva by instilling into the eye 

 a drop of ammonia, we can dissipate this redness by galvanising 

 the higher end of the cut nerve. In the same way the electrisa- 

 tion of the great cervical sympathetic nerve, or rather of the 

 higher cervical ganglion, determines the contraction of the pia 

 mater of the same side. 1 In dogs M. Yulpian has seen the 

 section of the renal nerves followed by red colouration of the 

 kidney, and by polyuria, with the passage of the albumine of 

 the blood in the urine. Inversely the electrisation of the 

 nerves made the renal gland grow pale and abolished the secre- 

 tion. In short, the electrisation of the sympathetic nerves 

 and ganglions produces results diametrically opposed to those 

 of their section and of their destruction, that is to say, paleness, 

 the lowering of the temperature, the abolition of the secretions, 

 the diminution of the sensibility. 



These phenomena are invariable. They are observed every- 

 where and always in all the vertebrates. There are consequently 

 vaso-motory nerves ; and M. Schiff thinks they should be 

 divided into vaso-constrictor nerves and vaso-dilatator nerves. 



Anatomically the remote vaso-motory nervous filaments have 

 been investigated as far as the capillaries of the second degree, 

 already furnished with nbro-cells. Evidently the nerves cannot 

 have direct action on the finest capillaries altogether destitute of 

 contractile elements. It is in acting on the arteries, the arterioles, 

 and the capillaries of the second and third degree that they 

 obstruct or facilitate more or less completely the passage of the 

 sanguineous current, modifying thus more or less the alimentary 

 ration of the organic elements. 



We have seen above that the ganglionary or grand sympathetic 

 nervous system, draws from the spinal marrow numerous and 



1 Nothnagel, DCS Nerfs Vaso-moteurs des Vaisseaux du Cerveau (analysed in 

 Gazette Hebdomadaire, 1867), and Callenfels, Ueber den Einfluss der vaso- 

 motorischen Nervens auf den Krewlauf und die Temperatur (Zeitschrift fur 

 ration. Med., 1855). 



