552 
Diseases  of  Cattle  and  Sheep. 
seasons,  on  undrained  soils  this  disease  prevails  to  such  an  alarm- 
ing extent  as  to  warrant  the  term  enzootic.  The  windpipe  and 
bronchi  become  filled  with  masses  of  worms  {Strongylus  flaria) 
and  mucus,  occasioning  violent  inflammation  of  the  membranes 
of  the  air-passages. 
The  entozootic  life  led  by  these  parasites  after  they  are  deve- 
loped in  the  body  is  tolerably  well  understood,  as  well  as  the 
ravages  they  commit ; but  their  origin  ah  ovo  from  the  heat 
of  the  sun’s  rays  on  the  stagnant  soil,  and  their  transmission 
afterwards  through  the  blood-vessels,  until  they  find  their  ap- 
pointed places,  are  phenomena  beyond  my  knowledge.  That 
they  are  the  product  of  spontaneous  production,  as  some  writers 
would  inculcate,  is  very  improbable  ; for,  if  so,  new  and  dissimilar 
species  might  be  formed  everyday  by  some  unknown  modification 
of  the  nutritive  process  which  gives  them  birth.  The  most  pro- 
bable opinion  is,  that  they  are  introduced  from  without,  and 
perhaps  undergo  several  changes  before  they  appear  in  the  in- 
ternal form. 
So  far,  the  task  to  trace  effects  to  causes  in  verminous  diseases 
common  to  sheep  and  cattle  on  ill -drained  lands  appears  not  very 
difficult.  There  is  something  palpable  to  the  mind,  although 
invisible  to  the  senses,  in  these  miasms  ; but  the  marsh  miasmata , 
the  supposed  agents  of  intermittent  fevers  amongst  the  rural  inha- 
bitants of  fen  districts,  as  well  as  fevers  of  various  kinds  amongst 
their  cattle,  which  prevail  more  or  less  at  certain  seasons  of  the 
year,  are  more  difficult  to  comprehend.  The  engineer  Ranch 
says  “ that  marshes  are  the  ulcers  of  the  earth,  which  blur  the 
fair  face  of  nature,  where  all  should  be  beauty;  and  from  these 
infectious  sores  the  languor  of  death  extends  far  and  wide.” 
D rainage  and  cultivation  have  done  much  in  reducing  the  extent 
and  insalubrity  of  the  marshes  of  England;  nevertheless  they  are 
still  found  in  many  districts,  which  defy  amelioration  by  the 
utmost  exertions  of  human  foresight  and  labour.  Those  of 
Lincolnshire  and  Essex  are  examples.  Kent,  Cambridgeshire, 
Chester,  Huntingdonshire,  Lancashire,  and  Stafford,  have  also 
extensive  marshes. 
Fevers  of  a typhoid  character  are  prevalent  amongst  cattle  in 
the  marsh  districts  of  those  counties ; indeed,  catarrhs , fevers, 
and  inflammations  assume  a more  depressing  character  on  marsh 
lands  than  on  the  upland  or  hilly  country  adjoining. 
Dysentery  and  red-water  in  cattle  are  diseases  also  common  to 
swampy  lands — whether  produced  from  the  insalubrity  of  the  air, 
or  from  the  stagnant  water  or  coarse  aquatic  herbage  with  which 
these  localities  abound,  is  not  exactly  determined.  Red-water  is 
attributed  by  many  veterinarians  to  the  change  of  temperature  of 
