700 



FUNCTIONS OF THE CEREBRUM 



[CH. XLVIII. 



methods, particularly the most sensitive one we possess, namely, the 

 methylene-blue reaction. 



Owing to the chemical action of the anaesthetic on the cells, the 

 Nissl bodies have no longer an affinity for methylene-blue, and the 



FIG. 508. Motiiliform enlargements on dendrites of nerve-cells, rendered evident by Cox's modification 

 of Golgi's method. A, in a cortical cell of a rabbit ; B, in a corresponding cell of a dog's brain, after 

 six hours' anaesthetisation with ether in each case. (Hamilton Wright.) 



cells consequently present what Wright calls a rarefied appearance ; 

 when this becomes marked the cells appear like the skeletons of 

 healthy cells. In extreme cases the cells look as though they had 

 undergone a degenerative change, and after eight or nine hours' 

 anaesthesia in dogs, even the nucleus and nucleolus lose their affinity 

 for basic dyes. The change, however, is not a real degeneration, and 

 passes off when the drug disappears from the circulation. Even 

 after nine hours' anaesthesia the cells return rapidly to their normal 

 condition, stain normally, moniliform enlargements have disappeared, 

 and no nerve-fibres show a trace of Wallerian degeneration. The 

 pseudo-degenerative change produced by the chemical action of the 

 anaesthetic no doubt interferes with the normal metabolic activity 

 of the cell-body, and this produces effects on the cell-branches. In 

 the early stages of Wallerian degeneration, the branch of the nerve- 

 cell which we call the axis-cylinder presents swellings or varicosi- 

 ties, produced by hydration or some similar chemical change. The 

 moniliform enlargements seen during the temporary pseudo-degenera- 

 tive effects produced by anaesthetics are comparable to this.* These 



* Some observers look upon the varicosities as artifacts. If they are, they 

 ought to have been found in all Wright's specimens, for the method of preparation 

 was the same throughout 



