224 
PRESERVATION  OF  LEECHES. 
confervas,  and  partly  from  the  effect  of  leeches  attaching  them- 
selves there.  This  unsightly  appearance  may  be  removed  by 
cleaning  the  glass  with  a  piece  of  rag  or  a  nail-brush. 
It  is  a  common  remark  among  Pharmaceutists,  that  the  sale 
cf  leeches  involves .  much  trouble  and  little  profit;  a  remark 
which,  before  adopting  the  plan  here  described  for  keeping  them, 
I  was  fully  prepared  to  coincide  with,  as  it  was  not  unusual  for 
me  formerly,  when  my  leeches  were  kept  in  the  old  way,  to  lose 
six  or  eight  in  a  day  or  two  from  my  little  stock.  But  I  am 
certain  that  if  the  aquarian  system  were  generally  adopted,  the 
complaint  referred  to  would  cease  to  exist.  I  have  now  tried  it 
for  two  years,  and  the  result  has  been  quite  satisfactory.  I  now  " 
scarcely  lose  more  leeches  in  a  year  than  I  did  formerly  in  a 
couple  of  days.  In  fact,  the  aquarium  supplies  to  the  leech  the 
conditions  under  which  it  lives  in  a  natural  state,  the  plant  af- 
fording oxygen  so  essential  to  animal  life,  and  in  return  receiving 
its  required  supply  of  carbonic  acid. 
Mr.  Redwood  inquired  whether  it  was  found  necessary  to 
maintain  any  definite  proportion  between  the  animal  and  vege- 
table life  in  the  aquaria. 
Mr.  Allchin  had  not  found  any  difficulty  in  that  res.pect.  One  1 
or  two  plants  sufficed  for  a  large  number  of  leeches.    The  num- 
ber of  snails  required  depended  upon  the  quantity  of  confervse 
present,  and  this  was  influenced  very  much  by  the  light  to  which 
the  aquarium  was  exposed. 
In  answer  to  other  questions,  Mr.  Allchin  stated  that  he  had 
not  found  it  practicable  to  keep  fish  with  the  leeches ;  the  latter 
attacked  the  fish,  especially  their  eyes,  to  which  they  fastened 
themselves,  and  they  soon  destroyed  their  prey  in  this  way.  He 
had  originally  expected  that  the  leeches  would  propagate  in  the 
aquarium,  but  in  this  he  had  been  disappointed. 
Mr.  Redwood  said  that  some  years  ago  experiments  were 
made  by  M.  Soubeiran,  Jim.,  of  Paris,  on  the  propagation  of 
leeches,  and  he  found,  with  a  view  to  that  object,  that  it  was  ne- 
cessary to  keep  them  in  ponds  having  clay  or  mud  banks,  which 
the  leeches  could  enter.  He  thought  that  some  modification  of 
the  aquarium  might  be  made,  by  which  this  condition  would  be 
fulfilled. —  Trans.  London  Pharm.  Society,  in  Pharm.  Jour. 
April,  1856. 
