396 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER . 
May  6,  1897 
the  centre  line  of  the  surface  have  carried  the  moisture  of  the  healthy 
plant  to  the  edges  to  keep  up  plant  circulation  ;  and  the  drops  you 
see  are  not  dew  drops,  hat  the  watery  juices  carried  out  by  the  energy 
of  the  healthy  plant.  For  place  the  lantern  under  an  unhealthy  leaf, 
and  you  will  find  no  drops  ;  there  is  no  circulating  vitality  in  it. 
Again,  examine  grass  blades,  and  you  will  find  large  drops  near  the  tips 
of  the  blades,  the  rest  of  the  blades  being  quite  dry.  The  large  drops 
seen  on  plants  at  night  are  falsely  called  dew  ;  they  are  produced 
from  the  plants  themselves  as  tokens  of  their  active  and  healthy 
growth. 
This  can  be  demonstrated  in  more  than  one  way.  Remove  a  branch 
of  Poppy  and  connect  it  by  means  of  an  indiarubber  tube  with  a  head 
of  water  of  about  40  inches.  After  placing  a  glass  receiver  over  it  to 
prevent  evaporation,  leave  it  for  three  hours.  Then  you  will  find  water 
has  been  freely  excreted  through  the  veins,  resembling  what  were 
familiarly  called  “dew  drops.”  If  the  water  pressed  into  the  leaf  is 
coloured  with  aniline  blue,  the  drops  when  they  first  appear  are  colour¬ 
less,  but  before  they  grow  to  any  size  the  blue  appears,  showing  that 
little  water  was  held  in  the  veins.  What,  then,  has  been  for  centuries 
called  dew  is  not  dew  at  all,  but  the  watery  juices  of  the  healthy 
■plants. 
But  look  over  dead  leaves  on  a  dewy  night,  and  you  will  see  a  fine 
pearly  lustre — that  is  dew.  Dead  matter  gets  equally  wet  when  equally 
exposed,  and  real  dew  is  not  so  common  as  is  generally  supposed.  On 
many  nights  on  which  grass  gets  wet  no  true  dew  is  deposited  on  it,  and 
on  all  nights,  when  growth  is  healthy,  the  exuded  drops  always  appear 
before  the  true  dew.  The  difference  between  the  true  and  the  false  dew 
can  easily  be  detected.  The  moisture  exuded  from  the  leaf  veins  of  the 
grass — false  dew — is  always  isolated  at  points  situated  near  the  tips  of 
the  blades,  forming  drops  of  some  size  ;  whereas  true  dew  collects  evenly 
all  over  the  blades.  A  glance  distinguishes  the  pearly  lustre  of  the 
dewy  film  from  the  glistening  diamond  drops  of  the  healthy  plant’s 
juices. 
But  whence  comes  the  dew  ?  It  does  not  fall  from  the  air.  Whence 
comes  it,  then?  We  shall  see.  Ground  a  little  below  the  surface  is 
always  warmer  than  the  air  over  it.  So  long,  then,  as  the  surface  of  the 
ground  is  above  the  dew  point  vapour  muBt  rise  and  pass  from  the 
land  into  the  air.  The  moist  air  so  formed  will  mingle  with  the  air 
above  it,  and  its  moisture  will  be  condensed,  forming  dew  wherever  it 
comes  into  contact  with  a  surface  cooled  below  the  dew  point.  In  fact, 
dew  rises  from  the  ground. 
Place  some  metal  trays  over  the  grass,  the  soil,  and  the  road  on  dewy 
nights.  You  will  generally  find  more  moisture  on  the  grass  inside  the 
trays  than  outside  ;  you  will  always  observe  a  deposit  of  dew  inside  the 
trays,  even  when  there  is  none  outside  at  all.  This  shows  that  far  more 
vapour  rises  out  of  the  ground  during  the  night  than  condenses  as  dew 
on  the  grass  and  the  objects. 
Pieces  of  iron  lying  on  grass  are  soon  surrounded  with  richer  grass, 
on  account  of  the  moisture  which  the  cold  metal  attracts  from  the 
rising  water-vapour.  Travellers  in  Australia  and  South  Africa  state 
that  they  often  found  the  under  side  of  their  waterproof  bedding  placed 
on  the  ground  to  be  wet  after  camping  out  at  night.  That  shows  that 
even  in  dry  countries  vapour  rises  from  the  ground  at  night.  I 
remember,  when  walking  in  the  vicinity  of  Hexham  with  an  acute 
observer,  trained  to  farming,  that,  on  my  remarking  that  the  farmers 
might  to  their  profit  remove  the  extraordinary  quantity  of  small  stones 
from  the  fields  in  order  to  give  room  for  the  growth  of  the  grain,  he 
shrewdly  said,  “  These  stones  collect  moisture  from  the  ground  ;  the  soil 
is  thin,  with  a  gravelly  subsoil,  and  unless  the  maximum  amount  of 
moisture  is  collected  (which  can  only  be  done  by  allowing  these  stones 
to  remain),  there  would  be  a  very  deficient  crop.  They  must  not  there¬ 
fore  be  removed.” 
Dew,  then,  rises  from  the  ground.  But  how  is  the  dew  formed  on 
bodies  high  up  in  the  air  ?  If  the  dew  comes  out  of  the  ground,  should 
it  not  be  found  on  bodies  only  exposed  to  the  earth  ?  Now,  dew  does 
not  rise  in  particles,  as  it  was  once  considered  to  fall  in  particles  like 
fine  rain.  It  riBes  in  vapour.  Some  is  caught  by  what  is  on  the  surface 
of  the  earth,  but  the  rest  ascends  in  vapour  form  until  it  comes  in 
contact  with  a  much  colder  surface,  to  condense  it  into  moisture.  The 
vapour  does  not  flow  upwards  in  a  uniform  stream,  but  is  mixed  in  the 
air  by  eddies  and  wind  currents,  and  carried  to  bodies  far  from  where  it 
rose.  In  fact,  dew  may  be  deposited,  even  though  the  country  for  many 
miles  all  round  is  dry  and  incapable  of  yielding  any  vapour.  In  such 
cases  the  supply  of  vapour  to  form  that  dew  would  depend  on  the 
evaporation  of  the  dew,  and  on  what  was  wafted  over  by  the  winds. 
But  the  most  practically  convincing  proof  of  the  rising  of  dew  from 
the  ground  is  in  the  form  of  hoarfrost  or  frozen  dew.  If  it  has  been 
a  bright,  clear,  sunny  day  in  January,  with  no  snow  on  the  ground,  look 
over  the  garden,  grass,  and  walks  on  the  morning  after  the  intense  cold 
of  the  night ;  big  leaves  may  be  found  scattered  over  the  place.  You 
see  little  or  no  hoar  frost  on  the  upper  surface  of  the  leaves,  but  turn  up 
the  surface  next  the  earth,  or  the  road,  or  the  grass,  and  what  will  you 
see  ?  You  have  only  to  handle  the  leaf  in  this  way  to  be  highly 
astonished,  A  thick,  white  coating  of  hoar  frost,  as  thick  as  a  layer  of 
snow,  is  on  the  under  surface.  Leaf  after  leaf  will  present  the  same 
appearance.  If  a  number  of  leaves  have  been  overlapping  each  other, 
then  there  will  be  no  coating  of  hoar  frost  under  the  top  leaves  ;  but 
when  you  reach  the  lowest  layer,  next  the  bare  ground,  you  will  find 
the  hoar  frost  on  the  under  surface  of  the  leaves.  Now,  that  is  positive 
proof  that  the  hoar  frost  has  not  fallen  from  the  air,  but  has  risen  from 
the  earth.  And  hoar  frost  is  frozen  dew. 
Dew,  then,  mostly  rises  from  the  ground,  and  what  used  to  be  thought 
dew  is  the  active  exudation  of  the  healthy  grass.  These  two  facts  are 
now  established.  Brilliant  globules  are  produced  by  the  vital  action 
of  the  plant,  showing  life  in  one  of  the  most  charming  forms  in  the 
phenomena  of  Nature. 
THE  YOUNG  GARDENERS’  DOMAIN. 
Amaryllis. 
These  very  useful  bulbous  plants  are  bo  rarely  seen  well  grown  that 
a  few  notes  on  their  culture  may  prove  helpful  to  some  reader  of  the 
“  Domain.”  Their  true  value  is  most  appreciated  when  arranged  for 
effect  in  a  conservatory,  although  they  are  useful  where  cut  blooms  are 
in  demand  for  decorative  purposes.  They  cvn  be  grown  so  as  to 
produce  a  succession  of  flowers  for  several  months  by  starting  the  bulbs 
into  growth  at  intervals  of  a  few  weeks.  We  grow  them  very  success¬ 
fully,  having  each  season  a  magnificent  display.  Several  bulbs  have 
produced  three  flower  spikes,  carrying  twenty-three  individual  flowers 
from  one  bulb.  They  are  grown  in  a  Peach  house,  where  the  tempera¬ 
ture  seems  to  suit  them  admirably. 
After  flowering  we  repot  the  bulbs  every  second  year,  removing  all 
offsets,  and  shaking  off  the  old  soil.  We  use  a  compost  of  three  parts 
good  fibrous  loam,  one  of  leaf  soil,  and  one  of  cow  manure  well  dried 
and  rubbed  fine,  with  about  one-fifth  part  of  silver  sand.  The  plants 
are  potted  firmly,  shaded  for  a  few  days,  and  placed  in  gentle  heat, 
where  they  are  grown  until  they  have  finished  their  growth.  They  are 
watered  regularly  until  the  foliage  shows  signs  of  maturation,  when 
water  is  gradually  withheld.  During  the  resting  season  the  bulbs  should 
be  watered  occasionally  to  prevent  their  shrivelling. 
I  think  the  best  mode  of  propagation  is  by  offsets,  although  plants 
may  be  raised  from  seed,  and  usually  flower  in  about  three  years.  A 
sharp  look  out  is  kept  for  insects,  and  any  that  may  be  detected  are 
quickly  destroyed. — J.  F.  D. 
[Will  our  correspondent  oblige  by  numbering  his  sheets?  The 
p’ants  referred  to  are  no  doubt  Hippeastrums.] 
Violet  Marie  Louise. 
There  areffew  flowers  that  excel  (in  a  combination  of  good  qualities) 
this  beautiful  double  Violet.  They  are  handsome,  and  continue  fresh 
and  fragrant  a  considerable  time  after  being  picked.  For  buttonholes 
they  are  exceedingly  valuable,  and  are  much  sought  after  by  both  sexes 
of  our  employers. 
A  small  bunch  kept  in  a  room  scents  the  air,  which  is  very  re¬ 
freshing,  but  too  much  of  the  scent  is  not,  I  think,  conducive  to  health. 
Speaking  from  experience,  it  has  a  tendency  to  cause  headache.  Never¬ 
theless  these  Violets  are  extensively  grown  for  their  scent  alone. 
They  are  of  easy  culture,  and  produce  abundance  of  blooms  through¬ 
out  the  winter — a  time  when  they  are  most  appreciated*  Judging  from 
my  experience  frame  rather  than  pot  culture  is  the  more  profitable, 
though  I  admit  when  they  are  grown  in  pots  in  a  house  there  is  one 
advantage— in  being  accessible  for  picking  from  in  severe  frosty  weather, 
when  those  in  frames  may  be  utterly  unapproachable.  The  soil  in 
the  frames  should  be  taken  out  to  the  depth  of  4  feet,  then  leaves  of 
the  previous  autumn’s  collecting  trodden  firmly  in  to  within  about 
15  inches  of  the  glass.  On  the  bed  should  be  placed  9  inches  of  a  good 
compost  of  loam  and  well-decayed  leaf  mould  in  equal  parts  to  receive 
the  roots,  planting  generally  being  done  about  the  last  week  in  August. 
Before  lifting  the  plants  (presuming  they  have  been  planted  out  in  the 
open  for  the  summer)  it  is  a  good  plan,  unless  rain  has  been  plentiful,  to 
give  them  a  thorough  soaking  the  day  previous,  as  the  soil  is  then  not  so 
liable  to  fall  away  from  the  roots,  and  flagging  of  the  leaves  is  greatly 
diminished. 
They  should  be  planted  about  8  inches  asunder,  making  them  firm  and 
being  careful  not  to  bury  the  crowns  too  deeply,  which  I  have  noticed 
is  a  great  drawback  in  several  respects.  Planting  being  finished  the 
whole  ought  to  be  well  watered,  when  the  plants  will  soon  commence 
flowering  and  continue  throughout  the  winter.  Should  they  show  signs 
of  red  spider  the  foliage  must  be  well  syringed  two  or  three  times  a  day 
unless  the  sun  is  very  hot. 
The  lights  should  be  placed  over  them  as  soon  as  cold  nights  set  in, 
always  propping  them  up  for  the  admission  of  air,  except  in  case  of 
severe  frost,  or  the  leaves  will  soon  turn  mouldy.  They  need  picking  over 
occasionally,  as  any  decaying  leaf  soon  contaminates  those  adjacent  to 
it,  and  a  mass  of  decay  follows  which  is  very  detrimental. 
For  supplying  the  stock  for  the  following  year  the  strongest  crowns 
ought  to  be  selected  and  pegged  into  the  soil,  all  others  being  cut  away 
as  they  appear.  An  occasional  supply  of  liquid  manure  suits  them. 
— Aspirant  . 
The  Melon. 
If  early  fruits  are  desired  sow  one  or  two  seeds  in  3-inch  pots  about 
the  middle  of  December.  Use  a  loamy  compost  with  a  little  leaf  mould 
added.  If  the  pots  can  be  plunged  in  a  hotbed  until  germination  takes 
place  so  much  the  better.  The  temperature  of  the  home  should  range 
from  65°  to  70°  by  night  and  70°  to  75°  by  day.  When  the  young 
seedlings  appear  take  the  pots  from  the  plunging  material,  and  arrange 
the  plants  as  near  the  glass  as  possible,  avoiding  draughts.  When 
nicely  rooted  place  in  5-inch  pots,  using  a  compost  as  before,  but 
rougher.  Do  not  be  too  liberal  with  water,  as  the  plants  soon  damp  off 
if  too  much  is  given.  The  pots  should  be  placed  on  a  shelf  about  1  foot 
from  the  glass  to  prevent  the  plants  from  becoming  drawn.  Aim  at 
sturdy  growth,  and  good  results  should  follow. 
