IMPAIRED NERVOUS CONTROL 185 



of the pancreatic hormone, is unfortunately common and 

 appears to become more so. A vast amount of study has 

 been devoted to it of recent years, and while no important 

 progress has been made in preventing the hormone-man- 

 ufacturing cells from going wrong or in replacing the defi- 

 cient hormone, as is done when the thyroid glands fail 

 to function, by administering material in the food, it has 

 been found possible in many cases to deal successfully 

 with the disease through a strict regulation of the diet. 

 Since the effect of pancreatic hormone deficiency is to im- 

 pair the ability of the tissues to use sugar, the method of 

 treatment is obviously through regulating the diet so that 

 the patient can get along without sugar. Up to the pres- 

 ent, this is the direction in which progress has been made. 



Impaired Nervous Control. — When one considers 

 the complexity of the adjustor mechanism in the higher 

 animals, together with the dependence of functional me- 

 tabolism on the operation of this mechanism, the possi- 

 bilities of disturbances in metabolism arising through 

 nervous impairments are seen to be manifold. The 

 impairment of nervous control can be attributed, in 

 general, to one of two things, actual destruction of nerv- 

 ous tissue whereby nerve pathways are broken, or alter- 

 ations in the metabolism within the nerve cells whereby 

 they are caused to function in some abnormal manner. 



Impairments Due to Tissue Destruction. — There 

 are various diseases whose symptoms are the direct result 

 of the destruction of nervous tissues. Among these is a 

 disease previously mentioned, locomotor ataxia, more cor- 

 rectly called tabes, in which there is destruction of nerve 

 tissue in the lower end of the spinal cord with consequent 

 interruption of important sensory pathways from the legs. 

 In the disease infantile paralysis, there is also a destruc- 

 tion of nerve tissue within the spinal cord, in this case 

 affecting motor nerve-cells and thus causing muscular 

 paralysis. In apoplexy there is injury to that part of the 

 brain whence proceed the nervous impulses by which 



