August  14,  1902. 
JOURNAL  GF  HORTICULTURE  AND  COTTAGE  GARDENER. 
159 
Societies. 
R.H.S.,  Scientific  Committee,  August  5th. 
Present:  Ur.  M.  T.  Masters  (in  the  chair);  Messrs.  Douglas, 
Hooper,  Bowles,  Saunders,  and  Baker;  Dr.  M.  C.  Cooke;  Revs. 
AV.  Wilks  and  G.  Henslow,  Hon.  Sec. 
Potato  tumour. — Dr.  Cooke  reported  on  the  specimens  sent  to 
the  last  meeting,  which  were  attacked  by  a  fungus  named 
Chrysophlyctis  endobiotica,  which  has  never  yet  been  described, 
though  the  disease,  Dr.  Masters  observed,  was  not  uncommon. 
Laburnum,  from  which  a  cluster  of  shoots  of  Cytisus  purpureus 
had  grown  out.  It  appears  that  the  tree  was  purchased  some 
twenty-seven  or  twenty-eight  years  ago  as  a  young  grafted  plant 
of  C.  purpureus  on  C.  Laburnum.  The  scion  grew  very  well  for 
a  year  or  two  on  the  stock,  till  a  strong  shoot  grew  out  below 
where  the  graft  was  inserted.  This  was  cut  off  to  save  the  graft, 
but  the  graft  died  quite  out  soon  afterwards.  The  stock  was 
left  to  grow  into  a  Laburnum  tree,  which  is  now  from  15  to 
20  feet  high,  and  as  much  in  diameter.  After  some  three 
or  four  years  the  C.  purpureus  made  its  appearance  in  various 
parts  of  the  Laburnum,  and  is  now  to  be  seen  in  tufts  all  over 
the  tree.  A  somewhat  similar  case  is  recorded  in  the 
“  Gardeners’  Chronicle  ”  (1857,  p.  382),  by  Mr.  E.  Purser, 
Larch  disease. — This  had  been  referred  to  as  a  fungus  of  the 
name  Allescheria  laricis,  which  was  unknown  to  Dr.  Cooke.  It 
turned  out  to  be  merely  a  “  MS.”  name  only,  with  no  description, 
and  afforded  no  solution  to  the  problem  of  the  disease. 
Silver  leaf  disease. — Dr.  Cooke  also  reported  upon  this  well- 
known  affection  of  species  of  Prunus,  which  has  been  found  by 
Professor  J.  Perceval  to  be  due  to  a  fungus,  the  hyphse  occurring 
where  the  roots  are  decayed,  which  produced  sporophores  of 
Stereum  purpureum.  By  inoculating  healthy  Plum  trees  with 
the  sporophores,  the  silvery  appearance  was  visible  after  eight 
or  nine  weeks.  The  infection  appears  to  take  place  be!owr 
ground. 
A  unanimous  vote  of  thanks  was  given  to  Dr.  Cooke  for  his 
three  reports,  which  will  appear  in  full  in  the  Society’s  Journal. 
Influence  of  scion  on  stock. — Mr.  W.  B.  Latham,  of  the 
Botanical  Gardens,  Edgbaston,  Birmingham,  sent  a  bough  of  a 
Clapham  Park.  He  wrote,  “  Some  few  years  ago  three  grafts  of 
the  Cytisus  (purpureus)  were  inserted,  and  now  the  whole 
character  of  the  tree  is  changing,  and  every  year  since  losing  the 
yellow  flower  of  the  Laburnum  and  producing  the  short  purple 
flower.” 
Cattlty a  and  Lcelia  cross- — Mr.  Douglas  exhibited  a  plant,  L.  C. 
Juno,  Edenside  var.,  being  C’.  Mossise  x  L.  majalis.  It  is  usually 
considered  an  invariable  rule  that  hybrid  Orchids  betray  the 
characters  of  both  parents.  The  present  plant,  though  an 
undoubted  cross,  was  thought  to  be  exceptional.  A  coloured 
illustration  which  Mr.  Douglas  exhibited  of  C'.  Mossise,  together 
with  the  plant,  showed  a  degree  of  yellow  in  the  throat,  which 
was  wanting  in  the  living  plant,  L.  majalis  has  a  very  spotted 
lip  ;  but  this  feature  was  also  wanting  in  the  plant.  That  a  cross 
or  hybrid,  though  usually  intermediate,  may  have  one  or  other 
parent  prepotent  is  well  known ;  but  the  second  generation,  as 
