42  5 
Report  on  the  North  American  Fever-tick,  have  shown  that  eggs 
which  were  submerged  for  a  period  of  from  ten  to  twenty-four  days 
nearly  all  hatched;  and  that  33  per  cent,  hatched  after  being 
submerged  for  twenty-five  days.  These  experiments  were  conducted 
in  order  to  ascertain  what  effect  the  flooding  of  pastures  would  have 
on  '  the  viability  of  ticks’  eggs  on  the  ground.’  These  authors  also 
proved  that  grass  lice  have  a  remarkable  resistance  to  water ;  and 
that  'flooding  under  some  conditions,  as,  for  instance,  during  a 
drought,  might  hasten  incubation.’ 
That  there  is  a  diminution  of  ticks  in  Jamaica  during  the  rainy 
season  has  already  been  pointed  out ;  but  it  is  clearly  evident  that 
this  is  not  brought  about  altogether  by  excessive  rains.  In  the  light 
of  our  present  knowledge  of  the  habits  of  the  Jamaican  species,  one 
can  only  conclude  that  the  dry  season  is  more  suitable  for  the 
development  of  the  ticks  than  other  times. 
DISSEMINATION  OF  CATTLE  TICKS  BY  VARIOUS  AGENCIES 
The  dispersal  of  ticks  has  been  brought  about  almost  entirely  by 
the  hosts  to  which  the  various  species  are  peculiar  ;  and  the  importa¬ 
tion  of  infested  cattle  into  various  countries  has  been  the  sole  means, 
practically,  by  which  these  pests  have  been  disseminated  over  the 
larger  portions  of  the  tropical  and  sub-tropical  parts  of  the  world. 
Man  alone  is  entirely  responsible  for  this  ;  ’and  it  is  only  during  recent 
years  that  any  steps  have  been  taken  to  enforce  quarantine  or  to 
control  in  any  way  the  movement  of  live  stock  on  their  introduction 
into  a  new  country.  The  question  of  rendering  a  tick-infested  country- 
free  from  these  animals  is  an  all-important  one  ;  and  even  if  this 
were  accomplished  on  a  relatively  small  scale  it  remains  to  be  seen 
how  best  such  an  area  can  be  protected  from  re-invasion,  as  there 
are  certain  agencies  by  which  this  could  be  brought  about  in  a  small 
way  other  than  by  the  careless  introduction  of  tick-infested  cattle. 
A  small  proportion  may  be  wind  borne,  though  it  is  doubtful  if  such 
an  agency  would  carry  ‘  grass  lice  ’  to  any  great  distance  from  an 
infested  area.  Hosts  unsuitable  to  the  development  of  the  Texas 
fever  tick,  such  as  dogs,  horses',  pigs,  goats,  or  other  domesticated 
animals,  or  even  man,  could  bring  this  about  in  a  small  degree,  so 
that  the  greatest  possible  care  must  be  exercised  in  dealing  with  this 
problem.  It  has  been  assumed  that  the  ‘  Bull  Frog’  (JBufo  marinvs) 
