128 



process of transmission, nor why it assumes one form 

 rather than another. Were the solution of the problem 

 attainable, it would doubtless reveal some singular mys- 

 teries In truth, we can only ascertain facts ; but 



this is quite enough, since the facts show by what concur- 

 rence of fortuitous circumstances and accidental causes 

 nature produces diversity." 



But to return to the consideration of heredity in connec- 

 tion with nervous diseases. It must be conceded that 

 heredity predisposes mankind not only to such diseases as 

 epilepsy and insanity, but to peculiarities in the mode in 

 which man is affected by minor ailments. For example, 

 how frequently do we recognise a predisposition to cephalalgia 

 in those families whose inheritance seems to have especially 

 influenced the nervous system ; also to dyspeptic troubles, 

 involving nausea, vomiting, and diarrhoea, and to the 

 manifold affections usually regarded as disturbances in the 

 vaso-motor system ? Not only so, but it is a well-known fact 

 that the members of certain families will live into old age, 

 however they may have subjected themselves, or been subjected 

 to pernicious influences during their lives; and notwithstanding 

 their being thus handicapped in the struggle for existence, 

 will contrast most favourably with those who apparently have 

 lived simply, carefully, and well. In connection with here- 

 ditary predisposition to diseases of the nervous system, Dr. 

 W. B. Carpenter says : "The fact seems to be that the nervous 

 system is so peculiarly liable to be shaped and modified by the 

 mode in which it is habitually called into exercise, that it 

 takes on a particular abnormal form of activity far more 

 readily than any other organ ; and thus, when a special form 

 of malnutrition has once established itself, this may be 

 transmitted to the offspring without the prolonged action of 



