﻿322 
  BOTANICAL 
  GAZETTE. 
  [ 
  December, 
  

  

  any 
  suspicions 
  that 
  the 
  prevailing 
  trouble 
  is 
  due 
  to 
  a 
  Pero- 
  

   nospora. 
  It 
  is 
  only 
  fair 
  to 
  give 
  the 
  Peronosporas 
  in 
  particu- 
  

   lar, 
  and 
  as 
  a 
  whole, 
  their 
  dues. 
  

  

  In 
  this 
  connection 
  it 
  may 
  also 
  be 
  noted 
  that 
  while 
  last 
  

   year 
  there 
  was 
  a 
  fair 
  abundance 
  of 
  the 
  rare 
  Peronosfora 
  

   Ctibensis 
  B. 
  & 
  C, 
  that 
  ruined 
  the 
  crops 
  of 
  hot-house 
  cu- 
  

   cumbers 
  in 
  this 
  locality 
  and 
  was 
  found 
  upon 
  field-squash, 
  

   pumpkins 
  and 
  cucumbers 
  generally, 
  during 
  the 
  present 
  

   season 
  it 
  has 
  almost 
  failed 
  to 
  appear. 
  This 
  is 
  a 
  surprising 
  

   fact, 
  for 
  with 
  the 
  wet 
  season 
  it 
  was 
  predicted 
  that 
  this 
  Per- 
  

   onospora 
  would 
  be 
  widespread. 
  No 
  oospores 
  have 
  yet 
  been 
  

   found 
  and 
  their 
  absence 
  in 
  a 
  species 
  that 
  preys 
  upon 
  short- 
  

   lived 
  annuals 
  in 
  our 
  climate 
  may 
  help 
  to 
  explain 
  the 
  coming 
  

   and 
  going 
  of 
  this 
  shy 
  mildew. 
  

  

  Peronosfora 
  efftisa 
  Rabenh. 
  was 
  to 
  be 
  found 
  quite 
  gen- 
  

   erally 
  upon 
  the 
  cultivated 
  spinach, 
  but 
  it 
  was 
  not 
  the 
  cause 
  of 
  

  

  Peronosfora 
  Fie 
  a 
  

  

  viux 
  luuLt,, 
  was 
  met 
  with 
  May 
  6th 
  abundant 
  upon 
  an 
  appa- 
  

   lently 
  new 
  host, 
  namely, 
  Ranunculus 
  abortivus 
  and 
  with 
  

  

  oospores 
  

  

  Peronosfora 
  alta 
  FI. 
  heretofc 
  

   upon 
  Plantago 
  major 
  and 
  P. 
  Ian 
  

   June 
  It 
  vyas 
  unusually 
  abundant 
  

   causing 
  the 
  plants 
  to 
  become 
  dv 
  

   yellow. 
  Oospores 
  were 
  present. 
  

  

  ■ded 
  

  

  :eolata. 
  During 
  May 
  anu 
  

  

  upon 
  Plantago 
  Virginica, 
  

  

  'arfed 
  and 
  turn 
  of 
  a 
  sickly 
  

  

  ,^„„ 
  . 
  ^- 
  mtry 
  is 
  P. 
  ohovata 
  Bonord, 
  

  

  ^und 
  upon 
  Spergula 
  arvensis 
  at 
  Liberty, 
  N. 
  Y. 
  Unlike 
  

   most 
  members 
  of 
  the 
  genus, 
  this' 
  prefers 
  the 
  stem 
  of 
  t 
  e 
  

   \xlC 
  '''PP^^^"'"g 
  in 
  patches 
  of 
  an 
  inch 
  or 
  less 
  in 
  length, 
  

   no 
  en 
  weakens 
  the 
  stem 
  so 
  much 
  as 
  to 
  cause 
  it 
  to 
  bend. 
  

   of 
  hi 
  r''""^'i* 
  "^^t^" 
  appears 
  upon 
  a 
  few 
  of 
  the 
  peduncles 
  

   tl 
  irkL 
  °'5 
  ^"florescence, 
  causing 
  the 
  infested 
  portions 
  to 
  

   count 
  ofTh 
  'T& 
  ^'^^^^^^ 
  than 
  the 
  normal 
  ones. 
  On 
  ac- 
  

   Sew 
  a' 
  \^^^^ 
  '^ 
  '' 
  ^^«y 
  to 
  detect 
  the 
  presence 
  of 
  th 
  

   ^Pon 
  an 
  .i^^'w^"' 
  ''S^ 
  ^^ 
  the 
  Peronospora 
  is 
  quite 
  constan 
  

   ■ 
  Thlfv 
  t 
  'fJ^^ 
  ^P^ts 
  ; 
  it 
  consists 
  in 
  the 
  development 
  of 
  

  

  pa?asi 
  c 
  ,?nl 
  T 
  "''" 
  ^P°" 
  the 
  host, 
  and 
  seems 
  to 
  be 
  strict 
  

   attent 
  on 
  T^ 
  "^'^ 
  "^^'^^^^- 
  This 
  matter 
  will 
  receive 
  furthe; 
  

   ticulariv 
  vvll/""' 
  '^"^"^^ 
  ^^" 
  opportunity. 
  The 
  species 
  is 
  P 
  ' 
  

  

  Theotoorf 
  "'"^'^' 
  ^^ 
  the 
  conidia 
  are 
  distinctly 
  °bo^t; 
  

   charaeteris,f 
  'r' 
  T"^ 
  ^^^e 
  those 
  of 
  other 
  species 
  and 
  

   wi'hthe 
  Pern'^ 
  '^'' 
  ""^- 
  ^t 
  may 
  be 
  said 
  in 
  passing 
  

  

  the 
  Peionospora 
  there 
  is 
  usually 
  upon 
  the 
  same 
  host 
  

  

  