THE HISTOLOGY OF DISSEMINATED SCLEROSIS. 653 



1. Developmental. 



In the discussion of the pathogenesis it was shown that Muller based his view 

 overwhelmingly on the presence of an endogenous (developmental) process, under 

 which naturally lay endogenous factors — inborn defects. One weak point in his 

 arguments, however, lies in the fact that the evidence of congenital anomalies in 

 the anamnesis is hard to find, or completely absent. Groups of cases occurring 

 in families also have only been reported in one or two rare instances, and in this 

 connection it must be remembered how great is the difficulty in the differential 

 diagnosis between disseminated sclerosis and certain atypical forms of hereditary 

 disease, and, further, that such cases might be family diseases with a symptom- 

 complex like that of disseminated sclerosis. Again, cases of congenital multiple 

 sclerosis are even more isolated. A neuropathic disposition has been alleged as an 

 important etiological factor, but this association has not been substantiated, and 

 where present no causal significance has usually been ascribed to it. Most observers 

 note that patients were normal both physically and mentally. 



Muller, in answering this argument of the absence of family forms and neuro- 

 pathic stigmata, points out that syringomyelia and glioma, attributed by numerous 

 writers to congenital disturbances of development, have also no hereditary forms, 

 and that heredity in nervous disease is seen chiefly in disease ol the true nervous 

 elements rather than in congenital anomalies of the glia. Nonne, who has examined 

 the phenomena of inhibition of cobra poison haemolysis in organic diseases of the 

 central nervous system, states that this cobra reaction is specially frequent in the 

 psychoses which are claimed as types of endogenous etiology. As he has found it 

 present in disseminated sclerosis more frequently than in any other organic disease 

 of the central nervous system, he claims that this reaction supports the view of the 

 endogenous nature of the disease. Nonne himself, however, gives indications in his 

 paper that this result must be accepted with great reserve, for the reaction is found 

 in general paralysis, admittedly an acquired disease. 



Furstner and others speak of " an early invalidity of the central nervous system," 

 which is unloosed by later accidental factors. It is evident that such views do not 

 bring the solution of the problem much nearer, yet it must be admitted that in some 

 cases " congenital anomalies of development may be present in the sense that they 

 lay the foundation of the constitutional tendency which renders the individual more 

 susceptible to the injurious influences of later life " (Mott). Such anomalies may 

 be insufficient to give rise to any symptoms till the onset of these later factors, but 

 they indicate a diminished resistance or a diminished vitality of the nerve elements 

 such as Gowers postulated for Friedreich's ataxia (' - abiotrophy "). 



2. External Factors. 

 Among the more immediate factors must be considered the following : trauma 

 (physical shock), psychical shocks, chills, infections, and intoxications. Modern 

 TRANS. ROY. SOC. EDIN., VOL. L, PART III (NO. 18). 91 



