501 
were  almost  entirely  among  negro  children,  showing  their  very 
marked  susceptibility  at  an  early  age,  and  it  was  also  found  that  the 
tendency  to  enlargement  of  the  spleen  was  greater  among  coloured 
children  than  among  those  of  purer  negro  blood. 
On  the  banana  estates,  where  unfortunately  the  number  of 
children  examined  was  smaller,  the  percentage  was  very  high,  in  two 
instances  reaching  loo.  This  was  among  the  coolie  population. 
In  this  parish  the  average  size  of  the  spleen  was  two  and  a  half 
times  the  normal. 
In  the  parish  of  St.  Mary,  where,  with  the  assistance  of  the 
District  Medical  Officers,  Drs.  Ritchie  and  Farquharson,  I  was  able 
'to  cover  a  very  considerable  area,  the  spleen  rates  were  also  found  to 
be  high,  an  average  of  457  per  cent.  Annotto  Bay  showed  a  spleen 
rate  of  69-8  per  cent,  falling  to  26  per  cent,  at  Enfield,  which  is  some 
two  or  three  hundred  feet  above  sea  level. 
The  influence  of  altitude  in  diminishing  malaria  was  shown  at 
Brown’s  Town,  where  no  enlarged  spleen  was  detected.  The  same 
was  found  to  be  the  case  at  Mandeville,  and  at  Betheltown,  both  at 
very  consideiable  elevations.  Chapelton  also  showed  no  enlarged 
spleens,  though  there  were  some  cases  of  malaria  in  the  hospital. 
This  method  of  examination  brings  out  the  marked  differences 
there  may  be  in  localities  which  are  contiguous.  For  example,  at 
Gieat  Pedro  Bay  the  percentage  of  enlarged  spleens  was  54  per  cent., 
whereas  at  Newell,  a  short  distance  off,  but  220  feet  above  sea  level. 
It  was  only  2*9  per  cent.  This  was  clearly  due  to  the  character  of  the 
soil  affecting  the  breeding  places  of  mosquitoes.  At  Great  Pedro 
Bay  there  were  numerous  grass-grown  ponds  in  which  Anopheline 
larvae  could  be  found,  whereas  at  Newell  the  country  was  almost 
entirely  waterless,  the  soil  being  sandy  and  well  drained,  and  the 
water  supply  derived  from  a  few  deep  wells. 
St.  Catheiine  showed  similar  variations.  Salt  Pond,  swampy,  and 
situated  in  the  itiidst  of  the  banana  plantations,  artificially  irrigated, 
showed  a  percentage  of  69-2,  while  Spanish  Town,  long  with  a  very 
unenviable  reputation,  but  now  with  improved  surface  drains,  showed 
only  17-3  per  cent. 
In  the  Black  River  District,  one  sugar  estate  where  artificial 
irrigation  was  employed,  and  where  a  number  of  coolies  lived  in  the 
JJ 
