564  Effect  of  Noxious  Gases.  {Am  dS^'iST™' 
ascribe  the  difference  in  effect  to  any  organic  disease  but  rather  to 
the  imperfect  mixing  of  the  gases. 
In  all  my  experiments  I  have  found  that  the  smaller  the  animal 
the  sooner  it  succumbed  to  poisonous  gases.  My  first  experiments 
were  made  with  small  birds,  then  I  tried  mice,  after  which  I  bestowed 
my  attention  on  guinea  pigs,  finally  selecting  the  rabbit  as  a  base 
for  the  experiments  which  I  now  present. 
EFFECTS  OF  CARBON  DIOXIDE  ON  ANIMAL  LIFE. 
No.  I.  I  placed  a  rabbit  in  a  glass  cylinder  and  pumped  in  atmos- 
phere of  10  per  cent,  of  C02  and  90  per  cent,  of  air. 
After  one  hour  and  seven  minutes  the  rabbit  gave  no  indication 
whatever  of  being  affected,  so  I  released  it  and  allowed  it  to  run 
with  several  other  of  its  species,  the  effect  of  its  treatment,  contrary 
to  expectation,  was  great  exhilaration,  instead  of  stupefaction. 
Result. — 10  per  cent.  C02  and  90  per  cent,  air,  1  h.  7  m. 
inhalation ;  exhilaration. 
No.  2.  I  placed  a  rabbit  in  a  glass  cylinder  and  pumped  in  an 
atmosphere  of  25  per  cent,  of  C02  and  75  per  cent,  of  air  for  one 
hour,  at  the  end  of  which  time  the  animal  showed  no  indication 
whatever  of  being  affected  and  when  released  and  placed  with  the 
others  exhibited  as  much  liveliness  as  any  of  them. 
Result. — 25  per  cent.  C02  and  75  per  cent,  air,  1  h.  inhalation; 
unaffected. 
No.  3.  I  placed  a  rabbit  in  a  glass  cylinder  and  pumped  in  an 
atmosphere  of  50  per  cent,  of  C02  and  50  per  cent,  of  air.  At  the 
end  of  two  minutes  the  rabbit  showed  signs  of  being  affected. 
At  the  end  of  three  minutes  the  rabbit  commenced  to  gasp  regu- 
larly every  two  seconds. 
At  the  end  of  6  minutes  gasps  were  3  seconds  apart. 
4 
6 
"  8 
9 
10 
death  ensued. 
Result. — 50  per  cent.  C02  and  50  per  cent,  air,  17  minutes 
inhalation ;  death. 
No.  4.  I  placed  a  rabbit  in  a  glass  cylinder  and  pumped  in  an 
atmosphere  of  75  per  cent,  of  C02  and  25  per  cent,  of  air. 
