Aj;nJu0a^,Pi9oa5m-}  Expert  Testimony.  n 
such  opinions.  A  pharmacist  has  knowledge  of  the  doses  ordinarily 
prescribed,  and  from  his  reading  has  some  knowledge  of  the  symp- 
tomatology of  drug  poisoning ;  but  his  observation  has  not  been, 
like  the  physician's,  of  a  character  that  such  reading  may  be  assim- 
ilated therewith ;  and  there  thus  seems  to  be  a  valid  objection  to  the 
admission  of  his  answer.  Similarly  he  may  be  questioned  as  to  the 
harmfulness  of  adulterants  or  preservatives  of  food.  Here  again  his 
observation  is  not  of  such  a  character  that  his  answer  can  be  any- 
thing more  than  opinion,  and  the  line  of  his  studies  does  not  ordi- 
narily lend  authoritative  weight  to  his  opinion  on  such  topics.  But 
the  physician  occupies  a  different  position  in  respect  to  these  ques- 
tions. They  form  an  important  part  of  his  studies  and  are  integrated 
with  the  whole  mass  of  his  knowledge.  He  is  therefore  entitled  to 
express  an  opinion  concerning  them ;  and  although  he  may  never 
have  poisoned  any  one  with  boric  acid  or  salicylic  acid,  deliberately 
or  accidentally,  or  may  never  have  recognized  impure  benzoic  acid 
as  the  cause  of  stomach  and  kidney  disease-  in  his  patients,  his 
opinion  that  such  substances  can  and  do  injure  the  human  stomach 
and  kidneys,  should  be  accepted  in  evidence.  Absence  of  knowledge 
on  these  subjects,  should  not,  moreover,  be  twisted  by  an  expert 
witness  into  knowledge  of  absence  o:  injurious  effects. 
Other  cases,  however,  present  difficulties  to  a  physician  asked  to 
give  an  expert  opinion.  Thus,  on  matters  of  chemistry  and  phar- 
macy outside  his  experience,  his  opinions  are  ordinarily  of  very 
limited  value.  But  let  us  also  consider  cases  that  may  be  within  his 
experience. 
A  physician  who  has  observed  a  patient  during  life  and  has  not 
suspected  poisoning,  may,  after  the  death  of  the  patient,  have  his 
suspicion  aroused,  and  in  reflecting  upon  the  symptoms  he  may  see 
a  new  significance  in  them.  This  suspicion  may  be  confirmed  by  the 
post-mortem  examination  and  the  chemical  analysis.  His  honest 
opinion  based  upon  all  the  facts  may  then  be  different  from  one  pre- 
viously expressed  upon  partial  knowledge  or  even  embodied  in  a 
death  certificate.  Yet,  unfortunately,  he  is  exposed  to  animadver- 
sion because  of  his  change  of  view.  Still  more  difficult  is-  the 
question  presented  in  a  case  of  suspected  poisoning  to  a  physician 
who  has  not  seen  the  living  person  or  the  corpse,  but  is  asked  to 
express  an  opinion,  on  facts  described  by  others,  as  to  the  nature  of 
symptoms  during  life,  and  as  to  the  cause  of  death.    Here  the  ques- 
