io    ■  Constitution  of  the  Alkaloids.        {A January fi9oorm 
well-known  therapeutic  agent  as  caffeine  should  be  excluded  from 
the  family  of  alkaloids.  As  is  well  known,  the  word  alkaloid  is 
derived  from  the  Arabic  word  alkali  and  the  Greek  word  Eidos,  and 
means  "like  an  alkali."  The  word  alkali  is  derived  from  the 
Arabic  words  Al  and  Kali,  meaning  "  the  potash."  Alkaloids  are 
like  an  alkali  because  they  resemble  the  typical  alkali  ammonia  in 
possessing  alkaline  properties,  forming  stable  salts  and  'at  times 
being  volatile,  as  in  case  of  nicotine  or  coniine.  They  are  the 
organic  bases.  There  are  two  classes  of  alkaloids,  vegetable  and 
animal,  and  at  first,  in  the  early  part  of  this  century,  chemists  only 
considered  the  vegetable  alkaloids  as  bases,  assuming  that  the  ani- 
mal body  only  excretes  substances  of  neutral  or  acid  character  and 
never  basic  character.  Thus  Liebig  classed  such  products  as 
xanthine,  creatine,  etc.,  as  members  of  the  family  of  the  starches. 
Alkaloids  have  always  been  closely  associated  with  the  term  active 
principle,  and  whenever  an  alkaloid  was  isolated  from  a  drug,  it  was 
promptly  heralded  as  its  active  principle.  This  is,  of  course,  not 
the  case  necessarily,  for  in  some  drugs  that  contain  alkaloids  the 
active  principle,  as  far  as  the  use  of  the  drug  is  at  present  put  to  in 
medicine,  is  not  an  alkaloid.  Because  they  were  considered  the 
active  principles  of  drugs,  their  discovery  was  a  great  factor  in  the 
development  both  of  chemistry  and  of  medicine,  for  physicians  saw 
in  them  the  first  means  at  their  command  of  administering  exact 
doses,  and  chemists  saw  in  them  the  dawn  of  an  era  which  would 
bring  chemistry  closely  in  touch  with  medicine,  and  thus  ennoble 
the  science  of  chemistry  and  at  the  same  time  greatly  increase  its 
usefulness  and  importance.  The  words  uttered  by  the  great  physi- 
cian, Claude  Bernard,  are  hence  strictly  in  accord  with  the  trend  of 
medical  and  pharmaceutical  thought  ever  since,  "  La  premiere  con- 
dition de  tout  progres  pour  la  medicine,  c'est  l'emploi  de  substances 
bien  definies  qu'on  puisse  doser  exactement,  et  dont  it  soit  possible 
de  mesurer  les  effets."  From  this  we  see  that  Claude  Bernard  was 
the  father  of  chemical  assaying,  for  he  says  the  first  condition  of  all 
progress  in  medicine  is  the  use  of  substances  that  are  well  defined, 
and  whose  effects  can  be  measured  and  which  can  be  administered 
in  exact  doses.  It  is  a  curious  fact  that  as  far  as  is  known  nearly 
all  vegetable  alkaloids  are  derivatives  of  a  substance  which  is  a  closed 
chain,  while  nearly  all  animal  alkaloids  are  derivatives  of  substances 
that  are  open  chains.  As  you  all  know,  the  first  alkaloid  isolated  from 
