Etiology. — The  more  common  evidences  of  functional  nervous
derangements  which  we  so  often  encounter  to-day  (among  which  ma}'
be  mentioned  sleeplessness,  muscular  twitchings,  nervous  dyspepsia,
sick-headache,  haj^-fever,  morbid  fears,  sexual  debility,  melancholia,
etc.)  were  uncommon,  and  are  still  so,  in  certain  climates  and  among
certain  classes.
The  reasons  why  functional  nervous  derangements  are  more  common
now  than  of  old,  and  why  the  American  race  is  particularly  disposed  to
them,  has  been  made  the  subject  of  much  scientific  thought  and  discussion.
It  may  be  well  to  refer  to  a  few  of  the  causes  which  tend  to  promote
nervous  debility.     Practical  suggestions  may  be  afforded  by  so  doing.
