Editonal. 3 1 



is demonstrable that motor nerve-cells after prolonged activity- 

 undergo important chemical changes which results in a changed 

 reaction toward stains and in shrinkage of the nuclei and va- 

 cuolation and crinkling of the nucleus. Similar changes may 

 be assumed in cortical cells and these must play an important 

 part in producing sleep. 



Pfliiger has attempted a detailed chemical theory of vital 

 phenomena in which oscillatory motions of the molecules result- 

 ing from explosive decomposition and recomposition constitute 

 the active agents. It does not appear necessary to associate his 

 chemical theory with his physical ideas which, as is well known, 

 demand a physical continuum between all parts of the neuro- 

 muscular and glandular system — a meshwork with absolute 

 physical continuity and physiological conductivity, but even 

 without this physical continuity, which recent histological inves- 

 tigation renders doubtful it might be supposed that the gradual 

 destruction of substance, waste of oxygen and acumulation of 

 carbon dioxide might serve to illustrate, if not entirely explain 

 the intermittent character of sleep. The attempt is also made 

 to apply the same principle to the explanation of hibernation 

 and the analogous summer sleep of amphibia. The fact that 

 hyperremia as well as anaemia of the brain may produce uncon- 

 sciousness is perhaps simply explained by the supposition that 

 in the former case blood pressure operates mechanically, pro- 

 ducing disturbing oscillations. The great variety of nerve stim- 

 ulants owe their effect to changes induced in circulation, in the 

 nutrition of the cells, or secondary effects which indirectly pro- 

 duce these effects. Whatever view may be taken of the chem- 

 ico-physical causes of sleep it is still important to have a clear 

 idea of the physiological connex between these processes in va- 

 rious parts of the nervous system. It grows out of the ana- 

 tomical structure of the brain that nutritive and circulatory pro- 

 cesses will not be identically effected in all parts of the organ, 

 and it is by no means indifferent what relation and order pre- 

 vails in the variation of these proces, as in various portions of 

 the brain. Meynert, who has attacked this problem, as is well 



