588 
Valuation  of  Drugs  and  Foods. 
/  Am.  Jour.  Pliarm. 
K   December,  1899. 
(IB)  A  most  interesting  field  of  operation  in  determining  the 
value  of  drugs  is  opened  up  through  the  investigations  of  the  botan- 
ists of  the  University  of  Wisconsin  on  the  toxic  action  of  various 
chemicals  upon  plants.  The  several  papers  by  True,  Kahlenberg, 
JHIunkel  and  Heald,  in  the  Bot.  Gaz.,FJiarm.  Review  and  Bot.  CentralbL, 
are  all  deserving  of  careful  study.  We  may  say  in  a  general  way 
that  "  compounds  which  have  a  toxic  effect  upon  animals  are  gener 
ally  poisonous  to  plants,  although  we  find  different  degrees  of  sensi- 
bility to  the  same  compound  in  both  plants  and  animals." 
In  analyzing  the  osmotic  and  toxic  properties  of  different  sub- 
stances, True1  compares  them  with  cane  sugar,  proceeding  as 
follows : 
Different  strengths  of  solution  of  cane  sugar  are  made  up,  based 
on  the  molecular  weight  of  the  substance  in  the  requisite  number  of 
liters  required  to  give  the  concentration  desired.  He  places  spiro- 
gyra  filaments  for  twenty-four  hours  in  these  solutions  of  different 
strengths  and  notes  the  strongest  solution  in  which  they  will  sur- 
vive. This  strength  solution  is  termed  by  him  the  boundary  concen- 
tration, and  is  regarded  as  measure  of  the  purely  osmotic  action  capa- 
ble of  being  sustained  by  spivogyra.  Having  determined  this  point, 
he  calculates,  by  use  of  methods  in  no  way  involving  the  living 
cell,  the  concentration  of  the  solutions  of  other  substances  studied, 
which  have  an  osmotic  value  equal  to  that  of  the  experimental 
boundary  concentration  of  cane  sugar. 
The  results  of  experiments  of  this  kind  on  different  substances 
would  indicate  that  (i)  "  if  the  algae  survived  in  a  concentration 
greater  than  that  calculated  from  the  value  of  cane  sugar,  the  con- 
clusion would  necessarily  follow  that  the  substance  in  question  was 
less  harmful  to  plants  than  sugar.  This  condition  of  things  was  in 
no  case  realized.  (2)  If  the  algae  first  survived  in  the  calculated  con- 
centration, the  action  of  the  substance  would  be  purely  osmotic  and 
equal  to  that  of  cane  sugar.  (3)  If  the  algae  should  first  survive  in  a 
concentration  more  dilute  than  the  calculated  boundary  concentra 
tion,  the  substance  in  question  would  be  more  harmful  than  sugar." 
"  In  the  realization  of  the  third  case,  injury  by  one  or  both  of  two 
possible  methods  might  be  wrought  :  ( 1)  by  a  very  rapid  extraction 
of  water  from  the  cell  violence  might  be  done  to  the  protoplasm 
1  Bot.  Gaz.,  1898,  p.  408. 
