23 THE FACTORS OP OEGANIC EVOLUTION. 



Sequard s case. But considering the improbability that 

 the phenomena observed by him happened to be nothing 

 more than phenomena which occasionally arise naturally, 

 we may, until there is good proof to the contrary, assign 

 some -value to his results. 



Evidence not of this directly experimental kind, but 

 nevertheless of considerable weight, is furnished by other 

 nervous disorders. There is proof enough that insanity 

 admits of being induced by circumstances which, in one or 

 other way, derange the nervous functions excesses of this 

 or that kind; and no one questions the accepted belief 

 that insanity is inheritable. Is it alleged that the insanity 

 which is inheritable is that which spontaneously arises, and 

 that the insanity which follows some chronic perversion of 

 functions is not inheritable ? This does not seem a very 

 reasonable allegation ; and until some warrant for it is 

 forthcoming, we may fairly assume that there is here a 

 further support for belief in the transmission of functionally- 

 produced changes. 



Moreover, I find among physicians the belief that 

 nervous disorders of a less severe kind are inheritable. 

 Men who have prostrated their nervous systems by prolonged 

 overwork or in some other way, have children more or less 

 prone to nervousness. It matters not what may be the 

 form of inheritance whether it be of a brain in some way 

 imperfect, or of a deficient blood-supply ; it is in any caso 

 the inheritance of functionally-modified structures. 



Verification of the reasons above given for the paucity 

 of this direct evidence, is yielded by contemplation of it ; 

 for it is observable that the cases named are cases which, 

 from one or other cause, have thrust themselves on 

 observation. They justify the suspicion that it is not 

 &quot;because such cases are rare that many of them cannot be 

 cited ; Imfc simply because they are mostly unobtrusive, and 

 to be found only by that deliberate search which nobody 

 makes. I say nobody, but I am wrong. Successful search 



