STIMULI AND THEIR ACTIONS 



377 



both those that produce motor impulses, and those that are 

 the seat of the sensations, of consciousness. In their anaesthe- 

 tising action upon the cells of the central nervous system lies the 

 extraordinary practical importance of the narcotics. Through the 

 abolition of sensations, especially of pain, they confer enormous 

 benefits upon mankind. But their misuse, especially that of 

 alcohol and morphine, by inflicting irreparable injuries upon the 



FIG. 169. Ganglion-cells of a morphinised dog, stained by Golgi' 

 most of the protoplasmic processes have assumed a monilifor 



s method. In A all, and in B 

 : orm appearance. (After Demoor.) 



cells, produces most destructive effects and transforms the benefit 

 into a serious evil. 



Recently a number of investigators, such as Meynert, Lepine, 

 Duval, Solvay and others, have put forward the view that gang- 

 lion-cells possess the power of amoeboid motion, their protoplasmic 

 processes, or dendrites, being able to shorten and lengthen. Hence 

 it is highly interesting to show, as Demoor ('96) has very recently 

 succeeded in doing, that under the influence of morphine in nar- 

 cosis, and also of other stimuli, distinct phenomena of contraction 

 can be observed in the dendrites of the ganglion-cells, or neurons, 

 which correspond exactly to those contractile phenomena that 



