74:6 FUNCTIONS OF THE CEREBRUM [CH. L. 



Lugaro's failure to find these appearances is doubtless due to his 

 not having maintained the anaesthesia long enough in his dogs. 



Wright started his work with a bias in favour of Demoor's bio- 

 physical theory, but he soon found that the theory was untenable ; 

 the results of his observations have shown him that the action of 

 anaesthetics is biochemical rather than biophysical, and he has been 

 led to this conclusion by the employment of other histological 

 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 

 cells consequently present what Wright calls a rarefied appearance ; 



FIG. 457. Mouiliform enlargements on dendriles 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 biain, after 

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



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 



