June  23,  1004. 
JOURNAL  OF  HORTICULTURE  AND  COTTAGE  GARDENER, 
537 
stem  assumes  a  per¬ 
fectly  perpendicular 
position,  the  petals 
change  their  colour, 
ultimately  falling  off, 
while  the  seed  vessel  re¬ 
mains  in  a  topsy-turvy 
position.  In  the  case 
of  varieties  where  the 
pitchers  are  distin¬ 
guished  by  a  crimson 
shade  of  colour,  the 
flowers  have  a  range  of 
hue  from  deep  crimson 
to  various  shades  of 
pale  ■  red  and  pink. 
Several  of  them  are 
sweetly  scented.  Under 
artificial  cultivation 
two  crops  of  flowers  are 
produced,  as  are  also 
two  crops  of  pitchers, 
the  flowers  in  each  case 
preceding  the  pitchers. 
Daelingtonia  cali- 
FORNiCA. — So  far  as  I 
know  there  is  only 
one  variety  of  Dar- 
lingtonia  in  cultivation, 
D.  c.  rubra  being  quite 
distinct  in  shape  and 
colour  of  pitcher.  We 
treat  this  somewhat  as 
-  for  Sarracenias.  Some 
have  experienced  diffi¬ 
culty  in  succeeding 
with  it.  While  the 
compost  used  is  the 
same,  not  quite  so 
much  water  is  given  at 
the  root.  I  find  the 
temperature  that  suits 
it  best  is  that  of  a  cold 
The  house  stands  about 
north  and  south,  and  at  the  north  end,  just  by  the  door  (which 
stands  open  all  day,  excepting  when  a  strong  north  wind  is 
blowing)  on  an  open  bench  over  the  water  tank,  they  luxuriate, 
and  the  pitchers  develop  into  giant  iwoportions. 
Vallisneria  spiralis. 
This  genus,  so  remai'kable  on  account  of  the  extremely 
curious  manner  in  which  the  process  of  fertilisation  is  effected, 
consists  of  two  species,  one  of  which  is  confined  to  Australia, 
while  the  other  is  widely  dispersed  over  the  tropical  and  warm 
regions  of  the  earth— both  of  them,  however,  inhabiting  only 
fresh-Avater  rivers  or  lakes..  V.  spiralis  the  be.st-known  species, 
and  the  one  commonly  grown  in  aquaria  in  this  country,  is 
found  Avild  in  many  parts  of  Southern  Europe.  It  is  a  perennial 
herb,  and  has  a  very  short  stem,  bearing  a  tuft  of  thin  narroAV 
green  grass-like  leaves,  hardly  a  quarter  of  an  inch  broad,  but 
often  a  yard  or  more  long,  with  their  apices  finely  saAV-toothed  : 
the  .stem  also  sending  off  suckers  from  its  .sides,  Avhich  ultimately 
take  root  and  produce  neAv  plants.  The  tAvo  .sexes  are  borne 
on  separate  plants.  The  male  floAvers  are  extremely  minute, 
Avhite,  and  of  a  globular  form,  Avithout  special  stalks,  but  .seated 
upon  and  entirely  covering  a  short  general  .stalk  of  a  conical 
form  ;  the  Avhole  being  enclosed  Avhile  .young  in  a  A-ery  short- 
stalked  spathe,  AAdiich  splits  into  tAvo  or  three  valves  at  maturity, 
Avhen  also  the  little  floAA'ers  become  severally  detached  from  the 
general  stalk,  and  rise  by  their  natural  buoyancy  to  the  surface 
of  the  Avater,  Avhere  their  three-parted  calyx  expands  and  per¬ 
mits  of  the  escape  of  the  pollen  from  the  anthers.  The  stamens 
var.v  from  one  to  three  in  number,  and  alternate  Avuth  several 
rudimentary  ones.  The  female  flowers  are  altogether  different 
from  the  males.  They  have  a  cylindrical  ovary,  bearing  three 
small  spreading  calyx-lobes  at  the  top,  and  contain  three  rudi¬ 
mentary  .stamens,  and  three  large  oval  often  split  stigmas.  Each 
floAver  is  enclosed  in  a  tubular  spathe,  borne  singly  at  the  end 
of  a  very  long  slender  spirally-tAvisted  .stalk,  which  uncoils  more 
or  less  according  to  the  depth  of  the  Avater,  so  as  to  alloAv  the 
floAver  to  float  upon  the  surface,  Avhere  it  expands  and  is  fer¬ 
tilised  b.y  its  stigmas  coming  in  contact  Avith  the  pollen  of  one 
or  more  of  the  very  numerous  detached  male  floAvers  floating 
about.  After  this  latter  process  has  taken  place  the  spiral 
stalk  coils  up  again,  and  by  that  means  conveys  the  floAA^er  to 
tile  bottom  of  the  AAater,  AA'here  it  produces  a  cylindrical  berry 
varying  from  half  an  inch  to  tivo  inches  in  length,  and  con¬ 
taining  numerous  cylindrical  seeds  marked  Avith  longitudinal 
ridges.  J  he  leaves  of  this  plant  form  an  exceedingly  beautiful 
object  under  the  microscope,  the  extreme  tenuity  and  trans¬ 
parency  of  their  cellular  tissue  alloAving  the  observer  to  Avatch 
the  movement  of  the  fluid  contents  of  the  cells _ (“The 
Ireasury  of  Botany.”) 
- - - 
Origin  ol  Parasitism  in  Fnngi. 
IMr.  George  Mas.see,  Principal  Assistant  in  the  Herbarium  of 
tlie  Koyal  Botanic  Gardens,  KeAv,  has  contributed  to  the  Philo- 
sophical  Transactions  of  the  Royal  Society  of  London  an  in- 
teresting  account  of  investigations  that  he  has  carried  out  on 
the  origin  of  parasitism  in  fungi.  The  research  also  throws 
much  light  on  the  factors  that  determine  the  immunity  of  cer¬ 
tain  species  of  plants  and  even  individuals  to  the  attack  of 
specific  fungi.  It  is  Avell  knoAvn  that  certain  parasitic  fungi 
have  the  poAver  of  attacking  with  ease  definite  crops,  Avhereas 
they  have  no  poAver  to  enter  the  tissues  of  other  crops,  even 
though  they  be  closely  related.  It  has  also  been  found  that 
even  varieties  of  some  particular  species  of  plant  may  be  i-e- 
sistant  to  the  inroads  of  a  parasite,  AA’hile  other  varieties  may  at 
once  succumb.  For  example,  some  Avheats  are  much  more 
lesistaiit  to  rust  than  other, s,  AA’hile  during  the  past  few  years 
vai  ieties  of  Turnip  have  been  raised  aa’IiicIi  have  special  poAA’er  of 
resi.stance  to  the  attack  of  the  parasite  that  causes  “  finger  and 
toe.” 
This  immunity,  or  comparative  immunity,  has  attracted  the 
attention  of  many  scientific  Avorkers,  and  noAv  Mr.  Massee 
claims  to  have  discovered  its  cause.  Formerly  it  AA’as  held  that 
an  individual  plant  AA’a.s  liable  to  invasion  by  a  fungus,  or  not, 
according  to  the  condition  of  the  atmosphere  at  any  particular 
time,  or  oAving  to  the  special  development  of  the  cuticle  cover¬ 
ing  the  leaves  or  stem.  Should  the  latter  be  specially  strong, 
then  it  Avas  believed  that  the  fungus  might  find  it  impossible  to 
enter;  on  the  other  hand,  if  the  cuticle  Avas  specially  thin,  the 
fungus  AAmuld  have  little  difficulty  in  effecting  an  entrance.  Mr. 
Massee’s  researches,  hoAvever,  go  to  show  that  small  differences 
in  character  of  the  sap  of  the  plant  tire  probably  the  main 
determining,  causes  as  to  Avhether  the  fungus  shall  be  able  to 
gain  an  entrance.  As  a  general  rule  it  Avas  found  that  if  a 
Aveak  solution  of  sugar  Avas  introduced  beneath  the  skin  of  the 
leaf,  and  if  the  spores  of  our  commoner  parasitic  fungi  AAere 
distributed  on  the  patch  so  treated,  the  fungus  had  the  poAver 
of  entering  and  living  on  the  sugary  solution,  and  eventuallv 
of  attacking  adjoining  tissues.  If,  on  the  other  hand,  a  AA’eak 
solution  of  acids  Avas  introduced,  the  fungus,  as  a  rule,  showed 
no  disposition  to  enter. 
Certain  fungi  are  purely  saprophytic,  that  is  to  sra’,  can  onl.A' 
live  on  dead  vegetable  matter;  and  yet  by  gradually  accustom¬ 
ing  them  to  push  their  tubes  into  living  plants  by  injecting  a 
substance  by  Avhich  the  fungus  is  attracted,  Mr.‘  Massee  has 
been  able  to  “  educate  ”  such  fungi  into  becoming  parasites, 
that  is  to  say,  fungi  capable  of  attacking  living  plants.  He 
comes  to  the  conclusion  that  all  para.sites  have  developed  from 
saprophytes,  and  that  it  is  quite  possible  for  a  harmlof3s  fungus 
living  on  dead  vegetable  matter  to  acquire  the  habit  of  living 
on  groAving  plants.  As  a  case  in  point,  he  cites  tlie  fungus 
Dendryphium  comosum,  Avhich,  until  recently,  appears  to  have 
been  quite  unable  to  attack  living  plants,  but  Avhich,  aided  by 
the  unnatural  conditions  under  Avhich  certain  glass-house  crops 
are  noAv  groAA  ii,  has  been  found  to  attack  in  a  serious  manner 
young  Cucumbers. 
Although  the  subject  of  inducing  saprophytes  to  become 
parasites  is  one  that  has  but  little  intere.st  for  the  practical 
farmer  or  gardener,  the  case  is  different  Avhere  the  problem  is 
attacked  by  the  botanist  from  the  other  sicle.  .Reference  has 
already  been  made  to  the  result  of  “  educating  ”  Turnips  ancl 
Avheat  to  resist  certain  diseases,  and  avo  also  knoAv  that  certain 
varieties  of  Potato  are  much  more  resi.stant  to  the  attack  of  the 
parasite  that  produces  Potato  disease  than  others ;  in  fact, 
immunity  to  disease  is  a  matter  constantly  in  the  minds  of  the 
raisers  of  iieAv  kinds  of  Potatoes. 
Doubtless  there  is  a  great  field  open  to  scientific  AA'ork  in 
this  direction,  and  it  is  a  subject  that  interests  the  forester  as 
Avell  as  the  fainier  and  gardener.  Although  the  task  of  pro¬ 
ducing  a  tree  Avhich  shall. proAm  resistant  to  the  attack  of  .some 
di,sease  must  proceed  much  more  sloAvly  than  in  the  ca.se  of  an 
annual  or  herbaceous  plant,  still  it  seems  not  to  be  beyond  the 
hounds  of  possibility  that  one  day  Ave  may  find  ourselves  in 
pos.session  of  a  variety  of  the  common  Larch  Avhich  Avill  prove 
immune  to  the  attack  of  the  Avell-knoAvn  “  Larch  Canker.” 
Vallisneria  spjralis  {male  plant). 
house,  Avhere  frost  is  just  kept  out. 
