344 LIST OF MICROSCOPICAL SPECIMENS. 



No. of diameters 

 No. magnified. 



157. Division and branching of fine nerve trunks, and 



distribution of fine pale fibres to capillary vessel. 

 The portion of the specimen under the microscope 

 is in an interval between two portions of a muscle 



(voluntary) from the neck 220 



Part of this preparation is represented in Plate XIX, 

 fig. 1. In this and several other specimens, the 

 fact of ihe existence of nerves to the capillary ves- 

 sels is positively demonstrated. I have elsewhere 

 adduced reasons for concluding that these with 

 the fine nerve-fibres ramifying in the proper tissue 

 of the cornea and other fibrous textures, those 

 around the uriniferous tubes and various gland 

 follicles, &c., constitute the afferent portion of the 

 system, to which belong, as efferent branches, the 

 so-called vaso motor nerves distributed to the arte- 

 ries. These two sets of fibres with the ganglia 

 common to both, constitute the self-regulating 

 mechanism, by which in health the equable flow of 

 nutrient matter to the various tissues and organs 

 of the body is maintained, and through which any 

 temporary disturbances are at once corrected or 

 compensated for. Anatomical observation does 

 not justify the conclusion so generally accepted, 

 that there is a special system of nerves presiding 

 in some mysterious way over the actual processes 

 of nutrition and change, going on in each individual 

 cell. And many of the facts taught us by experi- 

 ments on living animals receive a more satisfactory 

 explanation upon the view here advanced. For in- 

 stance, there is the interesting observation on the 

 foot of the living frog recorded in page 325. 



158. Experiment. The frog's foot arranged as to show the 



circulation small artery is to brought into the field of 

 the microscope. By gently touching the surface of 

 the skin, even at a considerable distance from the 

 point where the small artery is situated, it may be 

 made to contract violently. In this experiment, 

 the afferent fibres are irritated, an impression is 

 carried to the nerve centre, and by the disturbance 

 produced the efferent fibres are excited, and con- 

 traction of the artery results . . . . . . 215 



159. Fine nerve-fibres distributed to capillary vessels of 



the palate of the frog forming networks and 



