500 AN AMERICAN TEXT-BOOK OF PHYSIOLOGY. 



the former course, running down the sympathetic chain to the sacral ganglia, 

 and passing from these ganglia through the gray rami comniunicantes to the 

 sacral nerves. None of the fibres thus derived enter the nervi erigentes of 

 Eckhard. Of the various branches of the pudic nerves (rabbit), the nervus 

 dorsalis causes constriction of the blood-vessels of the penis and the peri- 

 neal nerve contraction of the blood-vessels of the scrotum. The course by 

 way of the pelvic plexus is taken by relatively few fibres. They run for 

 the most part in the hypogastric nerves, a few sometimes joining the plexus 

 from the lower lumbar or upper sacral sympathetic chain, or from the 

 aortic plexus. The presence of vaso-dilator fibres in the lumbar group is 

 disputed. 1 



The sacral group of nerves leave the spinal cord in the sacral nerve roots. 

 Their stimulation causes dilatation of the vessels of the penis and vulva. 



Internal Generative Organs (those developed from the Miillerian, or the 

 Wolffian, ducts). Langley and Anderson 2 find vaso-constrictor fibres for the 

 Fallopian tubes, uterus, and vagina in the female, and the vasa deferentia and 

 seminal vesicles in the male, in the second, third, fourth, and fifth lumbar 

 nerves. The internal generative organs receive no afferent, and probably no 

 efferent, fibres from the sacral nerves. 3 



The position of the sympathetic ganglion-cells, the processes of which carry 

 to their peripheral distribution the efferent impulses brought to them by the 

 efferent vaso-motor fibres of the spinal cord, may be determined by the nicotin 

 method of Langley. About 10 milligrams of nicotin injected into a vein of a 

 cat prevent for a time, according to Langley, 4 any passage of nerve-impulses 

 through a sympathetic cell. Painting the ganglion with a brush dipped in 

 nicotin solution has a similar effect. The fibres peripheral to the cell, on the 

 contrary, are not paralyzed by nicolin. Now, after the injection of nicotin the 

 stimulation of the lumbar nerves in the spinal canal has no effect on the vessels 

 of the generative organs. 5 Hence all the vaso-motor fibres of the lumbar 

 nerves must be connected with nerve-cells somewhere on their course. The 

 lumbar fibres which run outward to the inferior mesenteric ganglia are for the 

 most part connected with the cells of these ganglia. A lesser number is con- 

 nected with small ganglia lying as a rule near the organs to which the nerves 

 are distributed. The remaining division of lumbar fibres running downward 

 in the sympathetic chain, and including the majority of the nerve-fibres to the 

 external generative organs are connected with nerve-cells in the sacral gan- 

 glia of the sympathetic. 



The sacral group of nerves enter ganglion-cells scattered on their course, 

 most of the nerve-cells for any one organ being in ganglia near that organ. 



Bladder. Neither lumbar nor sacral nerves send vaso-motor fibres to the 

 vessels of the bladder. 6 



1 Franck, 1895, p. 143 ; Langley and Anderson, 1895, p. 93. 



2 Langley and Anderson, 1895, p. 129. 3 Langley and Anderson, 1896, p. 372. 



4 Langley, 1894, p. 420, also Langley and Dickinson, 1889, p. 423. 



5 Langley and Anderson, 1895, P- 131. 6 Langley and Anderson, 1895, P- 84. 



