732 
Supplement  to  the  “ Tropical  Agriculturist."  [April  1,  1897. 
means  merely  exact  knowledge— know leilge  reduc- 
ed to  a system.  But  what  have  I to  say  for 
theory  ? Well,  what  i.s  atlieory  ? The  word,  un- 
fortunately, has  a loose  and  degraded  meaning— a 
bad  meaning — as  well  as  the  strict  and  good  mean- 
ing in  which  it  is  used  in  science.  In  its  bad 
meaning,  whic’.i  is  not  very  deiinite,  but  has  vari- 
ous shades  of  badness,  it  stands  for  a useless  or 
groundless  speculation  which  leads  nowhere,  and 
which  is  not  tested  by  facts  or  practice.  But  that 
it  not  the  sense  in  which  we  use  it  in  science.  1 
am  inclined  to  think  in  this  .sense  the  non-scienti- 
tic  man  is  a greater  theorist  than  the  scientific. 
This  is  the  very  antitliesis  of  what  is  scientific. 
The  very  first  lesson  of  science  is  never  to  theo- 
rise in  this  sense. 
So  soon  as  we  have  accumulated  a mass  of  facts 
in  any  branch  of  knowledge,  tlie  mind  naturally 
seeks  an  explanation  of  them.  It  seeks  to  group 
them  together,  to  systematise  them  by  some  great 
common  circumstance  or  cause  which  produce.s 
them.  In  fact,  it  forms  a theory.  It  may  be  a 
wrong  theory,  but  at  least  it  is  based  on  facts, 
which  it  attempts  to  explain. 
But  all  the  history  of  science  shows  that  a 
wrong  theory  is  often  atr  ajjproximatiorr  to  the 
truth,  or  contains  some  germs  of  truth  itt  it.  A 
scientific  theory,  then,  mirst  rrot  only  be  air  ex- 
planation of  frrct,  but  it  must  not  be  inconsisteirt 
with  any  known  fact.  It  must  be  able  to  lit  iir 
with  aird  explaiir  everything  known  which  is  con- 
nected with  it-  If  it  does  not,  it  naust  be  modi- 
fied or  rejected.  Scierrtific  theory  is  therefore  a 
most  useful  thing.  It  is  a most  practical  thing. 
Not  only  does  the  clashing  of  rival  theories  when 
we  are  at  the  stage  before  we  have  arrived  at  air 
accepted  theory — always  lead  to  investigatioir  arrd 
inquiry  on  the  part  of  their  advocates,  each  anx- 
ious to  discover  everything  which  can  favour  his 
point  of  view  and  hence  lead  to  great  extension  of 
knowledge,  but  when  we  have  arrived  at  a correct 
theory  we  are  placed  in  a position  of  great  advant- 
age. We  now  have  an  explanation  of  certain  facts 
of  Nature.  Hence  we  are  so  tar  in  a position  to 
use  and  control  Nature  for  our  benefit,  because  we 
now  understand  her  working.  But  further,  and 
still  more  important,  we  never  arrive  at  a true 
theory  without  it  leading  to  developments,  often 
in  the  most  unexpected  directions.  We  can  never 
arrive  at  the  explanation  of  any  one  set  of  facts 
without  it  throwing  light  on  a host  of  others. 
There  is  no  department  of  natural  study  so  small 
and  mean  that  the  acquisition  of  a true  theory  re- 
garding it  will  not  improve  the  outlook  of  all 
human  knowdedge.  Some  of  you  may  know  how 
beautifully  Tennyson  put  this  thought  in  the 
poetical  words  : — “ Flower  in  the  crannied  wall, 
1 pluck  you  out  of  the  crannies  ; I hold  you  here, 
root  and  all,  in  my  hand,  little  flower— but  if  I 
could  understand  what  you  are,  rootand  all,  and 
all  in  all,  I should  know  what  God  and  man  is.” 
We  see,  then,  that  a real  theory  is  the  most  prac- 
tical of  things.  It  grows  from  facts  ; it  explains 
facts  ; it  increases  known  facts  ; it  never  loses  its 
hold  on  fact.s.  1 am  not  ashamed  to  in'oclaim 
myself  a teacher  of  theory.” 
In  concluding  his  able  address  I’rofessor  Hen- 
drick said  : — 
“ Now,  gentlemen,  1 must  not  try  your  patience 
any  longer,  but  endeavour  to  come  to  a close. 
But  just  let  me  ask — What  is  the  use  of  this  agri- 
cultural department!-'  Thi.s  is  for  you  to  deter- 
mine. 1 have  endeavoured  to  the  best  of  my 
ability  to  point  out  to  you  the  crying  need  there 
is  to  bring  onr  highest  training  and  research, 
whicii,  1 jiresume,  should  be  found  in  our  univer- 
sities, into  touch  with  onr  industries.  In  this 
district,  as  in  many  others  even  in  our  manufac- 
ing  and  commercial  Britain,  agriculture  is  the 
great  industry.  It  should  be  the  duty  of  this 
department,  then,  to  form  a centre  of  scientific 
knowledge  and  a centre  for  the  dissemination  of 
such  knowledge  in  the  agriculture  of  the  district. 
We  cannot  do  this  without  your  sympathy  and 
support.  Our  modern  agriculture  needs  to  have 
scientific  sjiecialists  placea  at  her  disposal,  brought 
into  the  closest  possible  relations  with  her,  not 
merely  as  analysts  and  commercial  scientists, 
but  as  teachers  and  advisers,  centres  for  the  crea- 
tion and  spread  of  knowledge.  The  modern 
agriculturist;  be  he  landlord,  factor,  farmer,  or 
be  he  a manure  merchant  or  manufacturer,  or 
other  follower  of  a business  depending  on  agri- 
culture, needs  to  know  a great  deal  of  the  sciences 
connected  with  agriculture.  Therefore,  he 
needs  to  be  taught.  From  these  classes,  there- 
fore, and  from  the  teachers  who  are  to  carry  the 
information  on  to  other  grailes  of  societj',  we 
ought  to  draw  students.  If  we  do  not,  we  are 
not  doing  our  duty,  or  you  are  not  using  your 
privileges.  Already  in  Germany  no  man  need 
ajiply  for  any  agricultural  post  of  importance  who 
has  not  a college  training  in  the  sciences,  as  well 
as  a field  training  in  the  practice  of  agriculture. 
Are  we  going  to  fall  further  behind  ? It  is  an 
ignoble  thing  to  be  spurred  on  merely  by  fear  of 
the  foreigner  ; but,  if  you  will  not  move  from 
higher  motives,  let  that  move  you.  Then,  even 
wiien  onr  men  are  taught,  they  cannot  know 
everything.  They  cannot  become  encyclop.aedias, 
carrying  all  the  information  of  all  the  specialists 
who  have  taught  them.  Therefore  we  need 
means,  such  as  are  supplied  by  the  universities 
and  research  stations  abroad,  to  bring  our  special- 
ists and  their  knowledge  freely  to  the  use  of 
agriculture.  We  are  here  to  be  used.  No,  gen- 
tlemen, the  world  has  changed,  and  we  must 
change  with  it  or  be  crushed  out.  If  the  days 
are  gone  when  we  can  get  >'3  [ler  cent.,  we  must  be 
content  with  2|.  If  the  days  are  gone  when  it 
was  enough  to  take  pains  with  our  hands  and  our 
feet,  we  must  take  pains  with  our  heads  as  well. 
We  must  call  to  our  aid  that  force  which  has 
changed  the  world  or  it  will  destroy  us.  I 
appeal  to  the  twentieth  century  for  my  justi- 
fication.” 
INSECT  BESTS. 
[Being  nelectiom  from  the  Report  of  the  Government 
Entomohxjist,  Gape  7'o?c//.] 
In  an  entirely  normal  state  of  nature,  the  re- 
lations between  plant-feeding  in.sects  and  their 
enemies  remain  jiractically  the  same  during  a 
serie.^  of  year.-;.  Tlu  se  enemies  are  predaceous 
animal',  .'ucli  as  snakes,  toads  and  birds,  and  pre- 
ilaceoiis  and  [mradi  ic  insects.  The  first  class,  that 
is  the  pred  iceeus  animal',  and  a part  of  the  second 
feed  with  little  discrimination  on  a great  v.iriety 
of  insects,  and  hence  their  inlluence  on  a particq* 
