﻿192 
  KEPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  

   PATHOGENIC 
  FUNGUS. 
  

  

  On 
  June 
  30, 
  1902, 
  it 
  was 
  noticed 
  for 
  the 
  lirst 
  time 
  that 
  man}^ 
  of 
  the 
  

   fry 
  in 
  some 
  of 
  the 
  rearing 
  bags 
  were 
  turning 
  white 
  and 
  d3nng. 
  The 
  

   entire 
  number 
  in 
  some 
  bags 
  eventually 
  died. 
  Upon 
  investigation 
  it 
  

   was 
  found 
  that 
  the 
  bodies 
  of 
  the 
  dead 
  fry 
  were 
  filled 
  with 
  the 
  mycelial 
  

   filaments 
  of 
  a 
  fungus. 
  

  

  This 
  growth 
  was 
  found 
  to 
  begin 
  in 
  most 
  cases 
  in 
  the 
  third 
  or 
  fourth 
  

   segments 
  of 
  the 
  abdomen, 
  where 
  the 
  first 
  indication 
  of 
  its 
  presence 
  was 
  

   the 
  opaque, 
  whitish 
  appearance 
  of 
  these 
  segments 
  in 
  contrast 
  to 
  their 
  

   almost 
  transparent 
  normal 
  condition. 
  It 
  soon 
  spread 
  throughout 
  the 
  

   body 
  of 
  the 
  fry, 
  destroj- 
  ing 
  all 
  the 
  internal 
  organs, 
  until 
  the 
  chitinous 
  

   shell 
  was 
  full 
  of 
  closely 
  packed 
  mycelium 
  (pi. 
  vi, 
  fig. 
  1). 
  

  

  The 
  fungus 
  was 
  isolated 
  in 
  pure 
  culture. 
  It 
  grew 
  on 
  the 
  ordinary 
  

   bacterial 
  culture 
  media, 
  and 
  was 
  also 
  cultivated 
  on 
  salt 
  water 
  agar 
  and 
  

   on 
  sterile 
  potato 
  and 
  bean 
  pods. 
  In 
  all 
  cases 
  the 
  aerial 
  growth 
  was 
  

   pure 
  white. 
  A 
  colony 
  growing 
  on 
  salt 
  water 
  agar 
  is 
  shown 
  in 
  figure 
  3, 
  

   plate 
  VI. 
  The 
  growth 
  is 
  a 
  branching 
  septate 
  mycelium 
  (pi. 
  vi, 
  fig. 
  2), 
  

   which 
  soon 
  breaks 
  up 
  into 
  a 
  number 
  of 
  short 
  segments 
  resembling 
  

   large 
  bacilli 
  (pi. 
  vi, 
  fig. 
  5), 
  and 
  probably 
  representing 
  arthrospores 
  or 
  

   conidia. 
  In 
  certain 
  filaments 
  the 
  formation 
  of 
  what 
  are 
  apparently 
  

   endospores 
  was 
  observed 
  (pi. 
  vi, 
  fig. 
  4). 
  

  

  Some 
  inoculation 
  experiments 
  were 
  made 
  with 
  the 
  fungus, 
  but 
  owing 
  

   to 
  the 
  lateness 
  of 
  the 
  season 
  when 
  the 
  fungus 
  was 
  isolated 
  young 
  lob- 
  

   ster 
  fry 
  were 
  not 
  to 
  be 
  had. 
  Inoculations 
  were 
  made 
  in 
  fish, 
  shrimp, 
  

   and 
  old 
  lobsters, 
  but 
  were 
  not 
  ver}' 
  successful. 
  

  

  The 
  fungus 
  is 
  to 
  be 
  classified, 
  presumably, 
  among 
  the 
  Oospores, 
  as 
  

   one 
  of 
  the 
  Hyphomycetace?e 
  of 
  the 
  fungi 
  imperfecta 
  Its 
  final 
  identi- 
  

   fication 
  and 
  complete 
  life 
  history 
  are 
  to 
  be 
  worked 
  out 
  at 
  some 
  future 
  

   time. 
  Its 
  origin 
  is 
  not 
  known, 
  but 
  is 
  probably 
  traceable 
  to 
  the 
  oily 
  

   menhaden 
  flesh 
  with 
  which 
  the 
  fry 
  were 
  being 
  fed, 
  thus 
  getting 
  into 
  the 
  

   intestinal 
  tract. 
  Another 
  season's 
  observations 
  will 
  be 
  necessary 
  to 
  

   determine 
  the 
  origin, 
  habits, 
  and 
  complete 
  life 
  history 
  of 
  the 
  fungus, 
  

   and 
  until 
  then 
  no 
  suggestions 
  can 
  be 
  made 
  as 
  to 
  methods 
  of 
  prevention. 
  

  

  CONCLUSIONS. 
  

  

  1. 
  The 
  principal 
  causes 
  of 
  death 
  in 
  artificially 
  reared 
  lobster 
  fry 
  are 
  

   cannibalism, 
  an 
  external 
  diatomaceous 
  growth, 
  and 
  a 
  pathogenic 
  

   fungus. 
  

  

  2. 
  Cannibalism 
  may 
  be 
  prevented 
  by 
  avoiding 
  overcrowding 
  and 
  by 
  

   providing 
  some 
  method 
  of 
  keeping 
  the 
  fry 
  continually 
  in 
  motion. 
  

  

  3. 
  The 
  diatomaceous 
  growth 
  may 
  be 
  prevented 
  or 
  to 
  a 
  large 
  extent 
  

   reduced 
  by 
  — 
  

  

  (a) 
  Filtration 
  of 
  the 
  water 
  supplied 
  to 
  the 
  hatchery. 
  

  

  (b) 
  Selection 
  of 
  a 
  place 
  for 
  the 
  location 
  of 
  the 
  rearing 
  apparatus 
  

  

  where 
  diatoms 
  are 
  least 
  abundant. 
  

  

  