8 
Expert  Testimony. 
f  Am,  Jour.  Pharm. 
\     January,  1905. 
spinal  cord,  although  of  course  he  had  seen  and  studied  sections  of 
cords  from  such  cases.  Some  physicians  have  never  seen  a  case  of 
infantile  scurvy  ;  but  they  know  that  the  affection  exists  and  that 
it  gives  rise  to  discolorations  of  the  skin  that  are  often  mistaken  for 
bruises,  and  upon  which  unfounded  charges  of  cruelty  to  children 
may*  be  brought.  I  have  never  examined  a  thyroid  gland  for 
iodin  or  arsenic,  yet  I  know  that  iodin  is  constantly  and  arsenic 
sometimes  found  in  thyroid  glands  of  men  and  animals,  apparently 
in  each  case  as  a  normal  constituent.  If  the  question  of  the  possi- 
ble presence  of  iodin  or  arsenic  in  normal  thyroid  glands  should 
be  of  importance  in  a  given  trial,  could  I  not  properly  state  my 
knowledge  as  book  knowledge  ?  Must  one  send  for  Mendel  or 
Gautier  to  testify  to  personal  analysis  ?  I  have  never  seen  an  insane 
person  commit  homicide  or  suicide,  yet  I  have  testified  in  court  that 
certain  persons  ought  to  be  kept  under  restraint  lest  they  should  kill 
themselves  or  others,  and  I  believe  that  the  testimony  was  properly 
given  and  properly  accepted.  Would  not  the  "no  hearsay"  rule 
exclude  this  testimony  also  ?  Even  had  I  seen  the  dead  bodies  of 
insane  suicides  or  of  the  victims  of  homicidal  maniacs,  that  fact 
would  not  seem  to  remove  my  knowledge  from  the  hearsay  cate- 
gory ;  nothing  would  do  that  except  actually  seeing  the  killing.  I 
know  that  arsenic  poisoning  has  been  caused  by  contaminated  beer, 
by  wall  paper,  by  stockings ;  though  I  have  never  analyzed  beer, 
wall  paper  or  stockings  for  the  presence  of  arsenic.  I  know  that 
in  this  city  fatal  lead  poisoning  has  been  caused  by  cakes  colored 
with  chrome  yellow,  though  I  did  not  see  any  of  the  cakes.  I  have 
not  even  seen  the  men  at  work  painting  or  making  lead,  whom  I 
have  treated  for  lead  poisoning  acquired  in  such  occupations. 
That  iodin  is  a  constant  normal  constituent  of  the  thyroid  gland, 
and  that  Gautier,  Bertrand,  and  others  have  found  arsenic  in  the 
normal  thyroid  gland  and  other  normal  tissues ;  that  maniacs  have 
committed  homicide  and  suicide  ;  that  arsenic  poisoning  has  been 
caused  by  contaminated  beer — are  facts,  not  opinions.  They  are 
facts  known  only  or  best  to  certain  persons,  because  those  persons 
have  made  special  studies  involving  the  knowledge  of  such  facts ; 
and  whatever  the  law  may  be,  it  would  appear  reasonable  that  when 
facts  of  this  order  are  relevant  to  the  issue,  qualified  persons  should 
be  permitted  to  testify  concerning  them  as  part  of  the  sum  total  of 
the  knowledge  acquired  by  reading  and  observation.    On  the  other 
