LITERARY NOIICES. 



The Trophic Function of Nerves. 



It is to be feared that teachers and investigators are prone to greatly 

 underestimate or ignore those functions of centrifugal nerves which fail 

 to express themselves in actual muscular contraction. Such acts as 

 perspiration, weeping and congestion are obviously under the control of 

 the nerves, and as long ago as 1S54 Virchow claimed that fever is an 

 expression of nervous activity. In addition to such temporary effects of 

 the nervous system on the vegetative, more permanent changes may be 

 noted, embracing atrophy, hypertrophy and hyperplasy, consisting in 

 the diminution or increase in organs through nervous influence. Para- 

 plasy, or the production of new structures from old ones, also occurs in 

 various forms as the result of neuropathies. 



The amount of influence exerted upon organs remote from nerve 

 centres and indirectly connected with them, both as regards function 

 and growth in abnormal conditions of the nervous mechanism, is sug- 

 gestive of the great influence of the nervous system upon the develop- 

 ment, correlation, and growth of the same organs under normal condi- 

 tions. From a most suggestive article by Professor Arndt on this 

 subject most of the following notes are compiled. (') 



It has long been recognized that the section of the trigeminal and 

 vagus nerves produce pathological changes in the mucous membrane of 

 the eye, nasal passages, mouth, and in the lungs. The fact that the 

 sensory nerves supplying these organs are of necessity simultaneously 

 cut has led to the suggestion that the irritation is due to external 

 sources which would have been perceived and removed but for the loss 

 of sensation. 



That this assumption is incorrect is shown by a comparison of cases 

 where gouty or rheumatic patients are prevented from the use of the 

 limbs because of joint affection, the motor nerves themselves being 

 relatively uninjured, with cases of paralysis due to central nervous dis- 

 turbance. In the former case there is no special tendency to decubitis 

 (a degeneration of the tissue in the extremities often accompanied by 



I Arndt, Rudod , " Ueber trophische Nerven," Archiv f. Anat. unci Phys. Physiol. 



Abth., 1891, p. 54. 



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