SIGNIFICANCE OF PHYLOGENETIC STUDIES 59 



Accurate investigation shows so often, that there is a slight 

 tremor and a disturbance of the equiUbrium along with some 

 disorder in the coordination of the muscles of the trunk and 

 of the extremities. The symptom of the spastic paresis in 

 sclerosis multiplex is caused by a lesion of the pyramidal 

 tracts, the accompanying symptoms of disorder of the 

 coordination must be due to an injury of the cerebro- 

 cerebellar pathways. Why do these tracts so often suiTer 

 in sclerosis multiplex? 



I shall now pass over other difficulties, only adding the 

 interesting fact, that the same clinical image may also be 

 found in cases, where the medulla oblongata and the medulla 

 spinalis do not show sclerotic foci, but where the cerebral 

 hemispheres only are afTected. 



Looking from the point of evolution it is easily under- 

 stood, that the tracts which conduct the stimuli for speech 

 are severely damaged in their function, while those for the 

 more simpler movements of the cranial nerves remain nor- 

 mal. The former are the socalled phonetic tracts which are 

 organized very late in phylogenesis and ontogenesis. 



The same holds with regard to the abdominal reflexes. 

 The term "reflex" is usually employed for mechanisms of a 

 lower order. There are, how^ever, several reflex movements, 

 which are the expression of a higher organisation and v/hich 

 appear very late in the phylogenetic and ontogenetic de- 

 velopment. To these belongs the abdominal reflex, which 

 is only present in primates, while the knee reflexes, on the 

 other hand, are found in several lower mammals. The 

 abdominal reflexes appear late in ontogenesis (Cattaneo, 

 Bychowski), they are not found until some months after 

 birth, while the knee reflex is always present in newborn 

 children. 



In this way we can also understand why horizontal nystag- 

 mus is so often found in sclerosis multiplex, while other forms 

 of nystagmus are rare. This symptom is usuall}^ caused by 

 the foci in the region of the Deiters' nucleus and of the pos- 



