v.] IN THE THEORY OF NATURAL SELECTION. 323 



Nothnagel thinks it possible or even probable that in those 

 cases in which the division of nerves is followed by epilepsy, 

 a neuritis ascendens— an inflammation passing along the nerves 

 in a central direction— is the cause of the changes suggested by 

 him in the epileptic centre. All our knowledge of bacteria and 

 of the pathological processes induced by them, seems to indicate 

 that such a neuritis ascendens, as is assumed by Nothnagel, 

 would render important support to the hypothesis that the 

 artificial epilepsy is due to infection. But when we further 

 consider that the offspring of artificially epileptic animals may 

 themselves become epileptic, although in most cases they suffer 

 from a variety of other nervous diseases (in consequence of 

 trophic paralysis), I hardly see how the facts can be rendered 

 intelligible except by supposing that in these cases of what I 

 may call traumatic "epilepsy, we are dealing with an infectious 

 disease caused b}^ microbes which find their nutritive medium 

 in the nervous tissues, and which bring about the transmission 

 of the disease to the offspring by penetrating the ovum or the 

 spermatozoon. 



Obersteiner found that the offspring were more frequently 

 diseased when the mother was epileptic, rather than the father. 

 This is readily intelligible when we remember that the ovum 

 contains an immensely larger amount of substance than the 

 spermatozoon, and can therefore be more frequently infected 

 by microbes and can contain a greater number of them. 



Of course, I do not mean to assert that epilepsy always de- 

 pends upon infection, or upon the presence of microbes in the 

 nervous tissues. Westphal produced epilepsy in guinea-pigs 

 by striking them once or twice sharply upon the head : the 

 epileptic attack took place immediately and was afterwards 

 repeated. It is obvious that the presence of microbes can have 

 nothing to do with such an attack, but the shock alone must 

 have caused morphological and functional changes in the 

 centres of the pons and medulla oblongata, identical with 

 those produced by microbes in the other cases. Nothnagel 

 also distinctly expresses the opinion that epilcps}^ 'does not 

 depend upon one uniform and invariable histological change, 

 but that the symptoms which constitute the disease may in all 

 probability be caused by various anatomical alterations, pro- 

 vided that they take place in parts of the pons and medulla 



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