Oct.  r,  1896.] 
THE  TROPICAL  AGRICULTURIST. 
24s 
SOIL  INOCULAIION. 
For  very  many  years  past  medical  men  liave 
practised  “ iiiocnlation  ” against  some  of  the  ills 
of  tlie  flesh,  bnb  inoculation  of  tlie  soil  for  the 
purpose  of  allbrding  to  plant  life  its  food  in  a 
suitable  form  is  a comparatively  new  idea. 
Agriculturists  are  now  to  have  an  innings,  and  the 
question  is  one  in  which,  no  doubt,  ))tanters  and 
agriculturists  generally  will  feel  keen  interest. 
Equally  should  it  prove  interesting  to  that  useful 
body  of  men  the  manufacturers  of  manures,  who 
may  very  possibly  have  to  vary  their  labours  of 
steaming  and  crushing  bones,  milling  poonacs, 
converting  lishinto  guano  and  grinding  phosphates, 
by  turning  their  attention  to  the  supplying  of 
pure  cultivations  of  different  forms  of  bacteria  ! 
How  soon  may  it  not  be  before  a planter  in 
ordering  his  annual  requirements  of,  say,  bones 
and  poonac  will  add  a request  for  so  many 
bottles  of  a suital>le  culture  of  bacteria  ? Plant- 
inri  Opinion  has  been  touching  the  fringe  of  the 
matter  in  the  correspondence  that  has  appeared 
in  its  pages  about  the  cultivation  of  coffee  without 
manure,  in  connection  with  the  shade-tree  Enj- 
thrian  lithospenna ; and  enquiry  has  thereby 
been  aroused  into  the  question  of  the  fer- 
tilising qualities  of  the  loppings  of  the 
leguminous  tree,  and  of  leguminous  crops. 
It  is  now  well  known  that  plant-life,  with 
the  exception  of  the  legumes,  does  not 
avail  of  the  free  nitrogen  of  the  .air  ; .and  th.at  the 
legumes  can  only  do  so  by  me.ans  of  the  b.acteria 
in  the  nodules  of  their  roots.  Nitrogen  is  not 
assimilable  in  its  free  form,  but  the  bacteria  in 
some  unknown  w.ay  convert  it  into  nitrates,  in 
which  state  it  can  be  t.aken  u])  by  the  plant.  It  is 
suggestive  that,  as  we  understand  in  the  case,  in 
soils  that  are  rich  in  nitr.ates  the  nodules  do  not 
appear  on  the  roots  to  anything  like  the  extent 
they  do  ivhen  the  soil  is  poor.  Of  course  to  the 
Ooff'ee-i)l.anter  tl.ie  particul.ar  benefit  of  leguminous 
shade-trees  is  tli.at  the  loi>i)ings  return  to  the  soil 
more  plant-food  than  they  have  taken  out  of  it 
for  in  their  conq)osition  are  nitr.ates  th.at  they  liave 
obtained  from  the  nitrogen  of  the  .air  that  is  in 
the  soil,  -through  the  agency  of  these  wonderful 
b.acteria. 
Now  if  coffee  trees  were  legumes  it  would  lie 
easy  to  stimulate  and  jiromote  their  growth  in  soils 
poor  in  nitrates,  for  we  read  in  the  August  num- 
lier  of  the  (Jontemporar]]  Remew  in  a most  interest- 
ing article  by  Mr.  C.  M-  Aikman  entitled  “ Ni- 
tragin,”  that  pure  cultures  of  the  nitrogen  fix- 
ing b.acteria  have  been  prepared,  by  the  usual 
bacteriological  methods,  suitable  for  the  commoner 
leguminous  crops  grown,  which  are  preserved  in 
glass  bottles  containing  agargelatine ; but — and 
this  is  a point  of  signilicance  to  the  Indian  agri- 
culturist— “they  have  to  be  kept  from  the  in- 
lluence  of  liglit,  and  core  must  be  letkcn  not  to  cx- 
])Ose  them  to  a tcinperutuvc  cil>ovc  !>8  ahrenheit. 
There  are  two  ways  of  affecting  inoculation  of 
the  soil,  either  by  putting  the  seed  in  a watery 
solution  of  the  preparation,  drying  and  then  sow- 
ing, or  by  wetting  fine  earth  or  sand  with  the 
solution  and  spreading  it  over  the  field,  after- 
wards workim.’’  it  into  the  soil  to  a depth  of 
about  3 inches.  Tlie  expense  of  this  latter  niethod 
is  said  to  be  the  modest  sum  of  five  shillings 
per  acre.  But  coffee  is  not  of  the  leguminous 
order,  and  how  then,  it  may  be  asked,  is  the 
planter  to  be  benefited.  Mr.  Aikman  tells  us  on 
the  authority  of  M.  Pasteur  that  soils  teem  with 
bacteria  which  may  be  present  to  the  number  of 
l,2b0  luillions  in  an  ounce  of  earth,  and  that  these 
convert  the  complex  forms  of  food  material  in  the 
soil  into  simpler  ones  easily  assimilable  by  plants  } 
thus  there  are  bacteria  that  turn  the  nitrogen  that 
is  in  the  soil  in  the  form  of  ammonia  into  nitrates. 
Liven  a soil  rich  in  its  natural  state,  or  enriched 
by  the  addition  of  fertilisers,  with  food  materials 
which  are  not  .assimilable  by  plants  owing  to  the 
absence  of  bacteria  that  may  be  necessary  to  effect 
the  conversion  of  such  materials  into  proper  nutri- 
ents, it  will  at  once  be  seen  how  valuable  would  be 
the  inoculation  of  the  soil  wdth  the  desired  bacteria 
of  the  right  type.  May  it  not  be  the  case  that 
enormous  quantities  of  manures  are  annually 
Avasted  owing  to  the  soils  to  Avhichthey  have  been 
applied  having  in  some  way  or  another  lost  their 
Supply  of  certain  forms  of  micro-organic  life? 
The  following  passage  from  Mr.  Aikman’s 
article  will  be  appreciated  by  those  wdio  have 
watched  the  discus.sion  about  tlie  nodules  of  legu- 
minous pl.ants: — “The  details  of  the proce.ss  of  nitro- 
gen-fixation, as  it  is  called,  are  not  as  yet  known 
wdth  any  accuracy.  That  the  organisms  found  in 
these  nodules  invade  the  roots  from  the  soil  and 
thus  give  rise  to  the  formation  of  the  nodules 
seems  to  be  clearly  proved.  There  they  multiply 
with  great  rapidity  and  stimulate  the  growth 
of  the  plant  cell.  Living  at  first  at  the  expense 
of  the  plant,  as  parasites,  they  gradually  be- 
come passive,  .and  the  cells  then  become  filled 
with  bacterioids  or  bacterium-like  bodies.  It  is 
when  this  period  is  reached  that  the  plant 
absorbs  the  contents  of  the  nodules,  and  leaves 
the  cells,  out  of  wdiich  they  are  formed  in  a 
limp  condition.  It  seems  doubtful  wdiether  there 
are  several  kinds  of  fixing  bacteria,  or  Avhether 
the  organism  becomes  so  altered  in  its  growth 
with  the  plant  that  it  is  not  .suited  for  promot- 
ing the  growth  of  other  leguminous  plants.  What- 
ever the  explanation  may  be,  it  has  been  found  that 
the  oig.anisms  suitable  for  effecting  the  fixation 
of  nitrogen  for  certain  plants  are  not  able  to 
act  in  the  same  capacity  for  other  plants.” 
In  addition  to  the  prmi.ary  object  of  the  Pasteur 
Institute  in  India, — the  tre.atment  of  rabies  by 
inoculation,  the  programme  of  the  Committee 
includes  the  treatment  of  cholera,  di]ihtheria, 
anthrax,  etc.,  and  the  promotion  of  independent 
b.acteriological  rese.arcli.  In  connection  wdth  the 
he.alth  of  the  immigrant  army  of  about  half  a 
lakh  of  coolies  .annually  into  Assam,  the  Indian 
'I’c.a  Association  has  not  been  slow'  to  recogni.se 
the  importance  of  the  Institute,  the  usefulness 
of  which  will  be  limited  only  by  the  funds  at 
its  (lisjiosal  ; .and  the  time  may  not  be  far  off' 
when  the  jdanters  of  Southern  India  through 
their  IL  P.  A.,  ni.ay  see  the  desirability  of 
supporting  it  with  the  view  of  investigation 
being  made  into  the  liacteriology  of  their  soils. 
— M.  Mail,  Aug.  29. 
^ 
BANANAS,  THF  FRUIT  OF  PARADISE. 
[liV  “KL  I’EIUTAI’.A,”  IN  POPULAR  .SCIENCE.] 
Bananas  w'ere  little  known  in  northern  lands  two  de- 
cades ago.  There  are  even  now  many  small  towns  in 
the  United  States  and  Canada  in  which  only  a few 
bunches  v/ill  supply  the  demand  for  a month.  There 
has  been,  nevertheless,  a great  growth  in  the  habit  of 
eating  this  fruit.  It  has  been  truly  said  that  the 
banana  has  made  over  the  appetite  of  races  who  a few 
years  ago  had  never  tasted  it,  a conquest)  quite  as  re- 
markable and  far  more  rapid  than  that  formerly 
made  by  the  potato. 
“Why  not!”  exclaimed  the  jolly  Vallejo,  when  I 
read  this  to  him  : “ That  is  as  it  should  be.  Surely 
the  gnieno  is  the  best  gift  to  Nature  to  man,  fordoes 
it  not  promote  leisurely  meditation  and  peace  ? Don't 
my  people  plant  a few'  «uras  with  the  mafas  of  the 
bananas,  and  >:o  escape  the  curse  which  befel  man- 
kind because  of  Adam's  transgressions?” 
