294 T. Brailsford Robertson: 



the processes underlying their activity, Accordingly the foUowing 

 investigations were undertaken. 



2. Experimental. 



/. On the Production of Acid in Nerve-Cells as a result of 



Excitation. 



It has been demonstrated that the „staircase" phenomenon 

 that is, the successive augmentation of the first few responses 

 to repeated Stimuli, occurs in the central nervous system.^) 

 As I will show in the sequel it is possible to induce a similar 

 augmentation of response through the action of substances 

 similar to those produced in nerve-cells as a result of their 

 activity. 



It has been pointed out by Mosso^) that the fatigue-pro- 

 ducts of nerve-centres and those of muscle are probably very 

 similar in nature, since mental fatigue is accompanied by signs 

 of muscular fatigue and vice-versa. We are fortunately in no 

 doubt as to the origin of these fatigue-products in the central 

 nervous System since no one has yet been able to demonstrate 

 directly chemical products of the activity of nerve-fibres. 

 Bethe's fibril-acids afford a possible exception^), but they 

 require enormously prolonged electrical Stimulation to evince 

 themselves and they may, not improbably, be disintegration- 

 products due to the chemical and structural changes which 

 nerves so rapidly undergo after removal from the body or 

 after otherwise undergoing injury;*) on the other band, they 

 may simply be among the varied products of prolonged electro- 

 lysis of organic Solutions. It is not probable that any very 

 great degree of chemical change accompanies the activity of 

 nerve-fibres, since the most deUcate methods fail to reveal any 

 production of heat as a result of prolonged Stimulation.^) Nerve- 



1) C. S. Sherrington, Sohäfer's Text-book of PhysioL, Edin- 

 burgh, 2, 841, 1900. 



2) Mosso, Arch. f. Anat. u. Physiol., PhysioL Abt. 1890, 129. 



3) Bethe, Allgemeine Anatomie mid Physiologie des Nerven- 

 systems, Leipzig 1903. 



*) Hardesty, Amer. Joum. of Anat. 4, 329, 1905. 

 6) Rolleston, Journ. of Phyeiol. 2, 208, 1890. 



