And  the  same  principle  is  sometimes  illustrated  with  great  force  in
single  famiHes.  Some  cases  are  referred  to  at  p.  730.  In  one  well
known  to  me,  a  lady  died  with  cancer  of  the  stomach.  She  had  seven
children  and  abont  thirty  grandchildren,  who  grew  np.  Some  of  them
are  still  living,  but  of  those  who  are  dead,  one  danghter  died  with  can-
cer of  the  stomach  ;  and  of  the  granddaughters,  two  with  cancer  of  the
uterus  and  one  with  cancer  of  the  breast ;  and  of  the  grandsons,  one
with  cancer  in  the  bladder,  one  with  cancer  in  the  rectum,  and  one  with
cancer  in  the  axillary  lymph-glands.  It  seems  unreasonable  to  call  a
disease  local,  which  can  pass,  by  inheritance,  with  so  complete  a  disre-
gard of  localities.  What  local  condition  or  disposition  can  we  suppose
to  have  been  transmitted  in  this  series  of  cases,  or  in  that  mentioned
at  p.  788,  in  which  cancer  occurred  in  different  organs  in  four  succes-
sive generations  ?'

For  the  cases  of  cancer  that  owe  absolutely  nothing  to  iaheritance —
I  suspect  them  to  be  few — can  we  trace  any  external  source  of  the
morbid  condition  of  the  blood  ?  Inoculation  and  contagion  are  the  only
probable  sources  of  the  kind ;  but  concerning  these  the  presumed  facts
are,  at  present,  very  few  and  uncertain.  There  are  cases  in  which,  by
the  inoculation  of  cancerous  material  into  the  bodies,  or  by  the  injection
of  such  naaterial  into  the  blood  of  dogs,  cancer  has  seemed  to  be  pro-
duced. I  think  that,  in  a  large  number  of  experiments,  that  result  has
been  three  times  obtained  ;  but  it  is  quite  possible  that  the  dogs  used
for  these  three  experiments  were  cancerous  before  the  human  cancerous
matter  was  injected  into  them  ;  for  cancer  is  indeed  a  frequent  disease
among  dogs.  The  instances  are  certainly  too  few  for  proof  of  inocu-
lation.
