144  A  Symposium.  {AVa^i9&r^ 
due  to  the  application  of  words  in  defiance  of  their  derivation,  and 
regardless  of  their  meaning.  This  is  seen  in  the  employment  of 
the  synonymous  terms  Pharmacology  and  Pharmacognosy  for  two 
different  subjects,  and  in  the  extension  of  the  term  Materia  Medica 
to  include  matters  wholly  beyond  its  proper  scope.  A  comprehen- 
sive and  correct  schema  would  be  about  as  follows : 
Pharmacology  or  Pharmacognosy,  the  science  of  medicines, 
divided  into : 
(1)  Materia  Medica,  their  description,  physical  properties,  chem- 
istry and  dosage. 
(2)  Pharmacodynamics,  or  Pharmadynamics,  their  powers  and  fate 
in  the  body,  divided  into : 
(a)  Physiological  Action,  in  small  and  full  doses. 
(&)  Toxicology ,in  lethal  doses,  including  their  antidotes  and  physi- 
ological antagonists. 
(3)  Pharmacy,  the  art  of  their  preparation  for  medicinal  use. 
(4)  Therapeutics,  their  use  in  disease. 
Of  course  many  subdivisions  could  be  made,  but  the  above  would 
form  the  main  schema,  would  be  consistent  and  readily  understood. 
Under  Materia  Medica,  a  subdivision,  Pharmachemics,  would  include 
solubilities  and  incompatibility.  Therapeutics  might  be  divided 
into  natural,  empirical  and  rational  therapeutics,  so  as  to  make  the 
subject  systematic  in  all  its  ramifications,  but  these  refinements  are 
outside  the  limits  of  your  question. 
Very  truly  yours, 
Samuel  O.  L.  Potter,  M.D.  (Jeff.), 
M.R.C.P.,  London. 
San  Francisco,  Cai,.,  January  25,  1904. 
My  dear  Kraemer : 
The  following  are  excerpts  from  papers  which  I  have  already 
published : 
It  would  seem  unnecessary  to  define  in  the  columns  of  a  medical 
journal  what  is  meant  by  pharmacology,  but  the  frequent  confusion 
of  this  term  with  pharmacy  by  those  who  are  not  teachers  of  medi- 
cine must  serve  as  a  reason  for  a  brief  statement  of  the  methods  and 
aims  of  this  branch  of  medical  science. 
The  vague  and  often  erroneous  use  of  the  word  pharmacology 
seen  in  earlier  writings,  as  in  the  definition  of  Nathan  Bailey  (1736), 
