INHIBITORY NERVES TO THE VASCULAR SYSTEM 97 



at the same time recognizing that the existence of such nerve 

 fibres is much less certainly proved than that of inhibitory nerve 

 fibres to other involuntary muscles, such as the retractor penis 

 and bladder musculature. With respect to the dilatation of 

 blood vessels in the skin brought about by stimulation of the 

 peripheral ends of sensory nerves I would suggest that an explana- 

 tion may be found in the following arguments. 



The condition of the epithelial cells of the skin is dependent 

 on the integrity of the sensory nerves (glossy skin, etc.). There- 

 fore the sensory nerves of the skin affect the metabolism of the 

 cutaneous epithelial cells. When the chorda tympani, which is 

 the secretory nerve to the submaxillary gland, is cut, a paralytic 

 secretion of the gland takes place and the gland cells atrophy. 

 When a sensory nerve is cut the epithelial cells atrophy and 

 glossy skin results. The sensory nerve may be considered to 

 control the metabolism of epithelial cells in a manner exactly 

 comparable to the control of gland cells by their secretory nerve. 

 Stimulation of the chorda tympani causes secretion, and that 

 secretion is accompanied by dilatation of the blood vessels of the 

 gland owing as suggested to the influence of acid metabolites 

 upon the vascular muscles. If stimulation of a sensory nerve 

 causes metabolic changes in the epithelial cells, corresponding 

 to those in the submaxillary glandular cells upon stimulation of 

 the chorda tympani, then the formation of acid metabolites 

 would cause dilatation of the blood vessels of the skin just as 

 in the case of the submaxillary blood vessels. 



