392 On the Ungual Corium and the Ungual Phalanx. [Dec. 15, 



2. The existence of considerable differences of potential between 

 two contacts upon the outer surface of the skin, and the fact that 

 such E.M.F. is capable of excitatory augmentation upon mechanical 

 stimulation, coincides with the assumption that the E.M.F. of the 

 current of rest is the outcome of glandular processes of variable 

 activity and is not compatible with the theory of origin of the E.M.F. 

 in mucin -metamorphosis. 



3. The reductions in the E.M.F. of the normal rest current follow- 

 ing exposure of the skin to carbonic acid gas and to the vapour of 

 chloroform, and the subsequent recovery upon admission of air, are 

 strong evidence that the origin of the E.M.F. is in some active vital 

 processes taking place in the skin, and ifc is reasonable to assume that 

 these occur in its secretory elements. 



4. The demonstration that the E.M.F. of the skin of the Eel under- 

 goes an excitatory variation as a result of electrical, thermic, and 

 mechanical stimulation, is in accordance with what is known to occur 

 in other glandular structures, and the fact that such excitatory change 

 manifests itself as a positive variation of the current of rest agrees in 

 the main with the phenomena observed in other cases. 



5. The fact that chloroform narcosis excludes the possibility of the 

 excitatory variation upon stimulation, at the same time as it reduces 

 the E.M.F. of the normal rest current to zero, supports the assump- 

 tion that the E.M.F. of the current of rest and that of the current of 

 action originate in one and the same source. 



6. Finally, the reduction of the E.M.F. of the normally directed cur- 

 rent of rest by atropinisation and the complete absence of any excita- 

 tory variation under such conditions, are facts strongly in favour of 

 the hypothesis that both the E.M.F. of the current of rest and that of 

 the current of action are from a glandular source. 



IV. " Preliminary Note on the Relation of the Ungual Corium to 

 the Periosteum of the Ungual Phalanx." By F. A. DlXEY, 

 M.A., M.D., Fellow of Wadham College, Oxford. Commu- 

 nicated by E. A. SCHAFER, F.R.S. Received November 22, 

 1892. 



The corium underlying the epithelium of the developing nail in the 

 human embryo is at an early age distinguishable from the cutis vera 

 of the remainder of the digit by its greater thickness and density. 

 Opposite the groove across the dorsal surface of the digit, which re- 

 presents the anterior border of the growing nail, the thick firm con- 

 nective tissue layer constituting the ungual corium does not thin out 

 or pass into the general corium ; but, still preserving its original 

 thickness, it sinks deeply into the substance of the digit, and travers- 



