May  1,  189T.] 
Supplement  to  the  “ Tropical  Agriculturists 
813 
these  animals  is  of  much  higher  degree,  and 
I believe  it  is  an  active  immunity  equal  to  that 
of  a beast  which  has  contracted  rinderpest  and 
recovered. 
It  is  particularly  important  to  know  that  only 
20  ccm.  of  such  serum  are  recpiired  to  immunise 
one  animal,  and  tlierefore  one  litre  (nearlj' 
Imperial  pint)  suffices  for  fifty  heail. 
My  further  investigations  concerning  this  wor/as 
operandi  will  aim  at  liudiug 
If  this  immunity  is  obtainable  in  a still  shorter 
period. 
If  a still  smaller  dose  of  serum  will  suffice  and 
if  it  may  be  attained  with  but  one  injection. 
A second  and  equally  important  fact  is  that  one 
is  able  to  immune  healthy  cattle  with  bile  of  such 
that  have  succumbed  to  rinderpest.  In  this  case 
only  one  hypodermic  injection  of  10  c.cm,  is 
sufficient. 
This  immunity  sets  in  on  the  tenth  day  at 
latest,  and  is  of  such  an  e.\tent  even  four  weeks 
afterwards  40  ccm.  of  rinderpest  blood  could  be 
injected  without  any  injurious  result.  I therefore 
conclude  that  the  immunity  produced  in  such  a 
manner  is  of  an  “active  ” nature- 
The  local  result  of  an  injection  is  merely  a hard, 
somewhat  painful  swelling  of  a size  of  a man’s 
list,  and  which  gradually  disappears  in  the  course 
of  a few  weeks,  provided,  however,  that  the  bile 
is  not  in  a state  of  decomposition  as  is  not  un- 
common when  an  animal  suffers  from  rinderpest. 
Under  such  circumstances  an  abscess  may  form, 
and  which,  however,  does  not  seem  to  be  detri- 
mental to  the  process  of  immunisation. 
Iloth  these  above-mentioned  facts  convince  me 
that  rinderpest  can  be  eradicated  with  but  little 
difficulty,  and  within  a comparatively  sliort  time, 
by  putting  these  methods  into  practice. 
The  method  of  immunising  cattle  with  serum 
may  be  used  in  order  to  separate  from  infected 
areas  those  tracts  of  country  which  are  still  free 
from  the  scourge  by  means  of  forming  a broad  belt 
between  them  in  which  all  the  cattle  are  in- 
oculated with  the  vaccin. 
The  protective  properties  of  the  bile  will  be  of 
inestimable  service  in  infected  parts.  Nearly 
every  case  of  rinderpest  supplies  a greater  or  lesser 
quantity  of  vaccin  for  those  animals  wdiicli  are 
still  healthy. 
I cannot  but  urge  upon  you  the  irapoitance  of 
bringing  this  method  immediately  to  the  notice  of 
those  cattle-owners  whose  animals  are  suffering 
from,  or  threatened  with,  the  disease,  as  1 am  sure 
thousands  of  cattle  may  daily  bo  saved  by  its 
application. 
The  modus  operayidi  is  very  simple  in  both  these 
methods,  but  it  will  nevertheless  be  desirable  to 
teach  as  early  as  possible  Veterinary  Surgeons 
and  other  person,^:  litted  for  such  wuu-k. 
I am  willing  to  give  a course  of  instruction  in 
the  Experimental  Station  in  Kimberley. 
It  may  further  be  advisable  ta  at  once  take  into 
serious  consideration  the  establishment  in  other 
parts  of  the  country  of  branch  stations  of  the 
Central  Laboratory  in  Kimberley,  to  furnish  them 
with  the  necessary  equipment,  and  to  appoint 
suitable  persons  to  take  cnarge  of  them. 
With  reference  to  your  telegram  dated  6th 
instant,  I beg  to  add,  that  1 do  not  consider  it  any 
more  essential  to  experiment  upon  camels,  as  our 
experiments  performed  on  cattle  have  been  so 
favourable. — (Signed)  It,  Koch. 
I’OTASII  IN  ULANTS  AND  THE  NEED  EUR 
SPECIAL  POTASH  EERTILIZERS. 
Some  months  ago  we  referred  to  the  belief 
that  was  gaining  ground  in  agricultural  circles 
that  tlie  value  of  potash  in  agriculture  was 
not  correctly  estimated  and  that  much  benefit 
was  to  be  expected  from  a,  more  extended  use 
of  kainit  and  other  special  potash  fertilizers. 
In  countries  where  no  particular  use  is  made  of 
ashes,  it  has  been  thought  sufficient  to  use  them 
for  supplying  all  the  potash  tliat  is  considered 
necessary  for  cultivated  plants.  The  amount  of 
potash  in  wooda.shes  and  other  refuse  substances 
used  for  suppling  this  ingredient  is  never  a 
uniform  quantity.  Thus  wood  ashes  that  are 
supposed  to  contain  5 j>er  cent  of  pure  potash 
are  frequently  found  to  have  not  more  than 
2 or  3 per  cent,  and  the  difference  in  the  potash 
value  of  wood  ashes  cannot  be  detected  by  its 
appearance. 
AVe  have  just  been  favoured  with  no  less  than 
three  publications  with  reference  to  the  value  of 
potash  in  agriculture,  two  referring  to  the  results 
obtained  in  the  United  States,  and  one  dealing  with 
experiments  in  Britain.  In  the  last  mentioned, 
entitled  “ Potash  Manuring— its  value  to  British 
Agriculture,”  the  authors.  Dr.  Aikman  and  Prof. 
AV right,  state  that  the  necessity  for  potash  manur- 
ing has  not,  liitherto,  received  the  recognition 
that  has  been  accorded  in  the  the  case  of  other  two 
important  plant  foods,  and  that  they(the  authors) 
have  set  themselves  to  examine  the  cause  of  this 
comparative  neglect  of  the  potash  manures,  and  to 
consider  how  far  the  neglect  is  justifiable  in  view 
of  the  results  of  a number  of  recent  experiments. 
It  has  not  yet  been  maile  quite  clear  what 
function  potash  exactly  performs  in  the  plant, 
but  that  no  plant  is  able  to  grow  without  it 
has  been  proved  again  and  again.  Soda,  wdiicl: 
is  an  essential  element  of  i)lant  food,  was  at 
one  time  thought  capable  of  replacing  potash 
but  tills  w'as  showm  to  be  false.  No  other  sub- 
stance can  replace  potash  which  is  a necessary 
constituent  of  all  plants.  It  is  a notewortliy 
fact  that  even  in  plants  grown  in  the  vicinity 
of  the  sea  potash  is  more  abundant  than  soda, 
although  the  latter  salt  is  thirty  times  more 
abundant  in  sea-water  than  tlie  former.  The 
quantity  of  soda  varies  very  considerably  in 
plant.s  according  to  circumstances,  but  nothing 
like  the  same  variation  is  found  in  regard  to 
pota.sh.  Its  functions  in  tlie  plant  though  not 
well  understood  are  known  to  be  important 
more  iuqiortant  than  those  of  any  other  ash 
constituent  except  phos})horic  acid.  According 
to  Liebig  it  plays  an  important  part  in  tlie 
distribution  of  the  carbohydrates  throughout 
the  plant.  It  is  always  to  be  found  in  the 
actively  growing  parts  of  vegetation,  as  in  the 
growing  buds  and  shoot.s,  and  exists  in  relatively 
large  proportions  in  the  seed.  In  wheat 
grain,  for  instance,  potash  forms  31  per 
cents  of  the  ash,  while  in  the  stem  it  forms 
less  than  11  per  cent.  In  the  ash  of  plants 
potash  occurs  chiefly  in  the  form  of  phosphate, 
chloride,  and  carbonate.  It  is  believed  that 
