SIGNIFICANCE OF PHYLOGENETIC STUDIES 57 



is rich in forms and in variations, still it cannot be denied, 

 that a certain group of symptoms dominates in the clinical 

 picture. These are especially spastic paresis of the legs 

 with increased reflexes and the Babinski's sign, disturbances 

 in coordination (tremor, ataxia), horizontal nystagmus, 

 slight dysarthry, the disappearance of the abdominal 

 reflexes. 



When some of these principal symptoms are missing, it is 

 hardly possible to diagnose sclerosis multiplex. Sensory 

 disturbances, abnormalities in the movements of the eye- 

 muscles, bladder and rectal functions remain in the back- 

 ground. They are very common in this disease, it is true, 

 but are less intensive and have a tendency to pass away. 



Several authors have tried to explain this contrast between 

 the clinical picture and the anatomical substratum, but no 

 satisfactory solution has yet been reached. So it has 

 been said that spastic pareses are so frequent, because the 

 pyramidal tracts are longer than the other tracts and hence 

 have a greater chance of being attacked by foci. Another 

 says that the disturbances in the sensibility seldom last, 

 since the sensory fibres are more resistant than the motor 

 ones. E. Miiller explained this fact by arguing, that more 

 ways are open for the conduction of sensory stimuli than 

 for motor stimuli. Still other authors believe, that it is 

 not possible to explain the chief symptoms of sclerosis 

 multiplex by circumscript, well-locahsed alterations of the 

 central nervous system. Hence they only speak of the 

 ^ ^general symptoms'^ of this illness. 



It is strange that no one has ever tried to consider all the 

 symptoms from one point of view. This is possible, in 

 my opinion, provided one places oneself at the point of 

 view of evolution. We must take for granted that the 

 older parts of the central nervous system, where the primi- 

 tive functions are regulated, resist noxious agents better than 

 the younger ones, where the higher functions are localised. 

 I shall give some examples from my own experience. 



