490 
that  the  clinical  types  are  undoubtedly  milder,  and  it  is  an  interesting 
speculation  whether  parasites  having  the  same  morphological 
characteristics  do  not  exhibit  in  different  countries  different  strains  of 
virulence.  It  is  also  probable  that  climate  and  other  surroundings 
affect  the  malignancy  of  the  attacks,  as  is  seen  m  cases  coming  to 
England  from  West  Africa. 
Prevalence  of  Malaria 
Cjeneral  and  Malarial  Death-rates. 
Before  discussing  the  question  of  anti-malarial  measures,  it  will 
be  necessary  to  endeavour  to  arrive  in  some  way  at  the  degree  of 
prevalence  of  malaria,  and  the  extent  to  which  it  affects  not  only  the 
death-rate,  but  the  general  health  and  efficiency  of  the  population,  and 
for  the  purpose  I  have  prepared  a  Table  (V)  showing  the  total  death- 
rate  from  all  causes  for  each  parish  in  the  Island,  the  total  death-rate 
from  malaria,  and  the  percentage  of  malarial  deaths  to  deaths  from 
all  causes  for  the  ten  years  ending  30th  April,  1907  ;  and  I  have  here 
to  acknowledge  my  indebtedness  to  the  Registrar-General  for  his 
kindness  in  supplying  me  with  the  figures  on  which  this  table  is 
based.  I  had  hoped  to  construct  a  similar  table  with  reference  to 
the  principal  towns  of  the  Island  so  as  to  arrive  at  the  malarial 
death-rate  of  those  places,  which  is  very  important,  because  the 
greater  number  of  the  important  centres  of  population  are  situated 
on  the  coastline  which  is  the  most  malarious,  and  it  would  most 
certainly  have  been  found  that  the  general  malarial  death  rate  of  a 
parish  is  much  influenced  by  the  inclusion  of  those  towns.  But, 
unfortunately,  the  records  do  not  appear  to  be  kept  in  such  a  form  as 
to  render  the  figures  for  the  principal  towns  readily  available. 
And  the  configuration  of  the  parishes  must  also  be  borne  in  mind. 
Without  exception  each  parish  reaches  to  the  sea,  and  has  a 
considerable  coastline,  the  inland  part  stretching  well  back  into  the 
interior  of  the  Island,  and  being  more  or  less  mountainous.  There 
are  no  parishes  entirely  inland.  Had  it  been  possible  to  draw  a  line 
round  a  considerable  portion  of  the  interior  it  would  certainly  have 
been  found  that  large  tracts  of  the  higher  parts  of  the  Island  are 
practically  free  from  malaria,  and  that  the  high  malarial  death-rate 
