and  it  was  eventually  proved  that  F  ilaria,  a  blood  worm  said  to  cause 
Elephantiasis,  whose  life  history  in  the  mosquito  had  been  fully 
worked  out  by  Sir  P.  Manson  twenty  years  before,  obtained  an 
entrance  to  the  human  body  through  the  proboscis  of  the  mosquito, 
while  the  brilliant  work  of  American  observers  in  Cuba  showed  that 
Yellow  Fever  was  transmitted  by  means  of  another  species  of 
mosquito,  namely,  the  Stegomyia. 
The  importance  therefore  of  the  mosquito  as  a  disease-trans 
mitting  agency,  and  the  necessity  for  its  reduction  and,  if  possible, 
its  complete  extermination,  has  been  clearly  demonstrated. 
V.  THE  NATURE  OF  MALARIA 
i  have  referred  incidentally  to  the  parasitic  nature  of  Malaria, 
but  for  the  benefit  of  the  laity  I  may  outline  briefly  the  life  history  of 
the  parasite,  its  mode  of  propagation  and  method  of  transmission, 
and  1  shall  confine  myself  to  facts  which  are  universally  recognised 
by  the  medical  and  scientific  world  and  accepted  by  them  as  being 
definitely  proved. 
Malaria  is  caused  by  the  admission  into  the  blood,  by  means  of 
a  mosquito,  and  so  far  as  we  know  by  that  means  only,  of  a  minute 
parasite.  If  we  examine,  microscopically,  the  blood  of  an  individual 
suffering  from  an  attack,  we  observe,  in  certain  of  the  red  blood  cells, 
a  minute  speck  of  protoplasm,  very  often  associated  with  small 
granules  of  black  or  dark  brown  pigment.  These  parasites  gradually 
increase  in  size  until  eventually  they  involve  the  whole  of  the  red 
blood  cells.  By  this  time,  the  purasite  has  undergone  a  process  of 
division  or  segmentation,  and  consists  of  a  body  containing  a  number 
of  rounded  spores.  Finally  the  body  bursts  and  the  spores  are  set 
free  in  the  liquid  of  the  blood,  where  they  eventually  attack  a  number 
of  fresh  red  cells,  and  the  process  is  repeated  until  the  blood  gets 
largely  destroyed,  and  the  patient  dies  or,  under  proper  treatment, 
the  parasites  die  out. 
Three  forms  of  parasites  can  be  distinguished  under  the  micro¬ 
scope,  each  differing  in  the  duration  of  the  life  cycle.  The  first  takes 
three  days  to  form  spores  and  causes  Quartan  Fever,  the  second  takes 
two  days  to  sporulate  and  produces  Tertian  Fever,  while  the  third 
produces  crops  of  parasites  at  irregular  intervals  and  forms  the 
Malignant  types  of  Fever  which  are  the  most  dangerous. 
