Magazine  of  the  School  of  Agriculture, 
61 
The  last  order  of  scolecid  worms  of  importance 
is  the  Nematoda  or  Nematoidea.  The  individuals 
of  this  order  are  cylindrical  vermiform  scolecids, 
sometimes  parasitic,  sometimes  free;  integument 
not  ciliated ; a well-developed  alimentary  canal; 
sexes  distinct  or  rarely  united.  The  Nematoda 
comprise  the  so-called  thread-worms  and  round 
worms,  most  of  which  inhabit  the  alimentary 
canal,  the  pulmonary  tubes,  or  the  areolar  tissue 
in  man  and  many  other  vertebrates.  Among  the 
more  important  members  of  the  parasitic  section 
of  the  Nematoda  may  be  mentioned  the  ascaris 
lumbricoides,  the  oxyuris  vermicularis,  the  tri- 
chocephalus  dispar,  the  sclerostoma  duodenale, 
the  dracunculus  medinensis  and  the  trichina 
spiralis.  The  first-mentioned  is  the  common  round 
worm  inhabiting  the  intestines  of  man  and  some- 
times of  other  mammals,  especially  the  pig,  often 
attaining  a length  of  several  inches.  The  second, 
commonly  known  as  the  “small  thread  worm” 
is  a gregarious  worm.  It  is  the  smallest  of  the 
intestinal  worms  of  man,  and  is  most  commonly 
found  in  children.  The  third  and  fourth  also  are 
parasitic  on  man.  The  fifth  known  ns  the  guinea 
worm  inhabits  during  one  stage  of  its  existence 
the  cellular  tissue  of  the  human  body,  generally 
attacking  the  legs  and  often  attaining  a length 
of  several  feet.  Trichina  spiralis  is  by  far  the 
most  important  of  this  species  of  worms,  though 
in  large  numbers  any  of  the  Nematoda  may  so  far 
interfere  with  digestion  and  nutrition  as  to  bring 
about  emaciation  and  dropsy  in  the  host,  and 
thus  render  the  flesh  unfit  for  food.  Since  the 
vast  majority  of  these  worms  inhabit  the  alimen- 
tary canal,  in  such  cases  where  the  intestines 
are  used  for  the  manufacture  of  sausages  &c., 
care  should  be  taken  to  subject  the  gut  to  pro- 
cesses which  will  ensure  the  destruction  of  the 
parasites,  their  ova  or  embryos,  ns  specimens  have 
at  times  been  found  adhering  to  the  mucous 
membrane  of  the  gut  that  has  been  used  for 
sausages.  The  trichina  spiralis  (which  has  its 
habitat  in  the  flesh  of  swine  alone)  is,  notwith- 
standing its  minute  size,  the  entozoan  that  is 
most1  to  be  dreaded  by  sanitarians.  We  shall 
consider  its  life-history  in  our  next  issue. 
A ROTATION  OF  CROFS. 
It  cannot  be  denied  that  the  adoption  of  a 
rotation  of  crops  where  practicable  is  the  most 
economical  and  intelligent  system  of  husbandry. 
The  reasons  for  so  doing  are  well  known,  viz., 
because  it  is  more  economical  of  manure,  as 
different  crops  require  different  ingredients  in 
different  quantities  ; because  for  the  same  reason 
it  is  more  economical  of  food  in  the  soil, 
different  crops  drawing  upon  such  food  in  different 
proportions  and  not  exhausting  particular  in- 
gredients ; because  it  allows  of  a better  distribu- 
tion of  labour  of  men  and  animals ; because  it 
allows  of  the  better  cleansing,  of  the  land;  because 
it  allows  deep-rooted  and  “air-feeding”  crops 
to  enrich  the  top  soil  for  the  benefit  of  the 
shallow-rooted  varieties  to  follow ; because  some 
crops  are  a good  preparation  for  others,  as 
leguminous  crops  for  cereals;  because  it  checks 
the  ravages  of  insects  and  fungi  by  shifting 
the  locality  of  the  crop  which  they  affect ; 
because  a better  supply  of  cattle  fodder  can  be 
Secured, 
Granted  even  that  crops  are  continuously’ 
grown  upon  the  same  soil  by  means  of  manure, 
still  the  system  is  a bad  one,  not  only  because 
it  is  a wasteful  one,  but  because  there  is  a 
tendency  of  certain  ingredients  to  accumulate  in 
the  soil,  and  the  balance  of  the  various  ingredients 
of  plant  food  to  be  interfered  with.  The  reasons 
ns  regards  the  economy’  of  manure  and  plant 
food  are  obvious,  while  the  fact  that  the  tendency 
of  crops  grown  in  rotation  is  to  mutually  benefit 
each  other  should  greatly’  weigh  with  our 
cultivators.  Again,  the  check  that  such  a system 
gives  to  insect  and  fungoid  attacks  is  of  the 
utmost  importance  to  tropical  agriculturists  who 
have  suffered  so  much  from  these  misfortunes. 
Our  esteemed  correspondent,  W.  A.  D.  S.,  writing 
from  Bombay’,  deserves  all  credit  for  his  effort 
to  convince  our  Ceylon  cultivators,  who  say’  that 
a rotation  of  crops  cannot  be  practised  under 
the  conditions  of  paddy  cultivation,  that  the  thing 
can  be  done,  and  that  he  (W.  A.  D.  S.)  has  seen  it 
done  in  North-Western  India.  He  has  thrown  out 
the  hint  that  Indian  Corn  and  lucerne  should 
form  part  of  the  rotation  with  paddy.  As  far 
as  our  experience  as  founded  on  our  own 
experiments  at  the  School  of  Agriculture  goes, 
we  believe  that  both  Indian  Corn  and  lucerne 
can  be  successfully  raised  on  paddy  soils  after  a 
little  special  preparation  of  the  land. 
GENERAL  ITEMS. 
The  substance  known  as  Ginseng  is-  so  highly 
valued  in  China  that  it  is  sold  at  from  20  to  250 
times  its  weight  in  silver,  and  sometimes  for  more 
than  that  price.  It  is  not  generally  known  that  the- 
drug  is  valued  as  a tonic  and  stimulant.  Ginseng 
is  the  root  of  Panax  quinquifolia.  The  collection 
and  preparation  of  the  root  for  the  market  were 
at  one  time  extensively’  carried  in  Canada,  and 
Ginseng  gathering  is  again  becoming  an  industry, 
The  plant  grows  in  China,  Manchuria  and  Corea, 
but  the  natives  are  loth  to  part  with  any  seed. 
The  wonder  is,  say’s  the  Medical  Press  and 
Circular,  that  with  a much  used  commodity  at 
such  a price,  steps  are  not  taken  to  cultivate  it 
insufficient  quantity  so  as  to  adjust  the  balance" 
between  supply  and  demand.  With  silver  in  the 
one  scale  and  the  highly  esteemed  root  in  the 
other,  it  seems  reasonable  to  conclude  that  the 
cultivation  of  Pana.v  quinquifolia  would  be  re- 
munerative whatever  the  cost  and  trouble.  Panax 
fructicosum  is  found  in  Ceylon,  so  that  it  is 
most  probable  that  P.  quinquifolia  may  thrive 
with  us.  We  had  an  opportunity  of  inspecting  a 
specimen  cf  Ginseng  for  the  first  time  a few  days 
ago.  From  the  section  shown  us  the  so-called  root 
would  seem  to  be  a rhizome  about  an  inch,  more 
or  less,  in  diameter,  of  a y’ellowish  colour  just  be- 
neath the  epidermis,  but  the  white  central  pithy 
portions  of  which  the  section  mainly’  consisted  was 
white  in  colour. 
Improved  ploughs  are  said  to  give  better  results 
than  the  native  ploughs  to  such  an  extent,  that 
the  superiority  of  the  former  is  now  an  axiom  at 
the  Cawnpore  Experimental  Farm  ; and  the  effect  of 
deep  ploughs,  where  effective  supervision  is  pos* 
sible,  has  confirmed  this  experience,  At  the  same 
time  the  adoption  of  the  improve^  plough  make| 
