354 



Mr. J. B. Power. 



[Feb. 16, 



make and break of the battery current as the test of excitability. 

 They find that the effect of the make excitation is increased when it 

 falls upon a katelectrotonic region, polar or peri-polar, that the effect of 

 the break excitation is diminished when it occurs in an anelectrotonic 

 region, polar or peri-polar, and that increase and diminution are more 

 marked in the case of the polar than that of the peri-polar region. 



They also tested the polar region by mechanical excitation, and 

 obtained evidence of increased excitability at the kathode, of 

 diminished excitability at the anode. 



The authors have also observed " after-effects " of polarisation 

 corresponding with the after-effects of electrotonus in the frog's nerve 

 as described by Pfliiger. 



The experiments were for the most part made on the peroneal 

 nerve, which was selected on account of its superficial course, and 

 the facility with which the muscular responses could be recorded 

 graphically. 



IV. " On the Excretion of Nitrogen by the Skin." By J. Byrne 

 Power, L.C.P.I. Communicated by Professor Emerson 

 Reynolds, F.R.S. Received February 7, 1882. 



During the years 1877-78, I conducted a series of experiments on 

 the excretion of nitrogen by the skin. Some of the data then obtained 

 were communicated at the Dublin Meeting of the British Association, 

 but I have since extended the inquiry, and now beg to submit an 

 account of the investigations. 



The results obtained by various experiments as to the existence of 

 nitrogen in the sweat have been contradictory. Voit, # Ranke,* 

 Parkes,t and others, relying on indirect methods, have denied its 

 existence, finding that the quantity excreted by the kidneys and 

 intestinal tract was equal to, and in some cases even exceeded, that 

 ingested, therefore leaving no room for any excretion by the skin. 



On the other hand, Anselmius.J Berzelius,§ Favre,|| Funke,^[ and 



* " Schmidt's Jahrb.," Bd. cxvii, pp. 1 — 10. Yoit made further experiments 

 on doves with confirmatory results. On the other hand, Seegen and Nowak made 

 subsequent experiments upon dogs with opposite results ; these again are contra- 

 vented by Grruber (" Virchow and Hirseh, Jahrgang," Bd. I, 1881, p. 163). I do 

 not myself believe that experiments on the lower animals are conclusive on this 

 point in human physiology. 



f " The Lancet," 1871, vol. i, p. 400. 



% Berzelius, " Traite de Chimie." Traduit par M. Esslenger. Tom. vii, p. 324. 

 Paris: 1833. 



§ Op. cit., p. 325. 



|| " Archiv Gen. de Med.," 1853, Tom. ii, pp. 1—20. 



% " Beitrage zur Kenntniss der Schweissecretion." Moleschott's " Untersuchun- 

 gen zur Naturlehre," iv, 36. 



