﻿50 
  

  

  water 
  is 
  near 
  the 
  temperature 
  of 
  37° 
  or 
  38°, 
  Farenheit 
  ; 
  if' 
  

   this 
  temperature 
  becomes 
  lowered 
  the 
  development 
  will 
  be 
  

   retarded 
  or 
  checked 
  entirely, 
  and 
  the 
  vital 
  processes 
  held 
  in 
  

   abeyance 
  until 
  the 
  temperature 
  again 
  rises 
  to 
  above 
  38°. 
  

  

  If 
  the 
  temperature 
  of 
  the 
  water 
  is 
  raised 
  much 
  above 
  38°, 
  

   as 
  in 
  the 
  case 
  already 
  mentioned, 
  the 
  eggs 
  are 
  merely 
  forced 
  

   forward, 
  as 
  vegetables 
  and 
  i)lants 
  are 
  forced 
  in 
  a 
  hot 
  house, 
  

   and 
  we 
  find 
  the 
  young 
  fish 
  developing 
  very 
  rapidly. 
  The 
  

   coldness 
  of 
  the 
  water, 
  and 
  the 
  subsequent 
  cold 
  snap 
  lowering 
  

   Btill 
  more 
  the 
  temperature 
  of 
  the 
  water, 
  was 
  undoubtedly 
  the 
  

   cause 
  of 
  the 
  exceedingly 
  slow 
  differentiation 
  which 
  took 
  

   place 
  in 
  the 
  eggs 
  up 
  to 
  the 
  20th 
  of 
  March. 
  It 
  has 
  been 
  

   known 
  for 
  a 
  long 
  time 
  tliat 
  snail 
  eggs 
  could 
  be 
  impregnated, 
  

   development 
  started, 
  and 
  then, 
  by 
  means 
  of 
  cold, 
  be 
  kept 
  in 
  

   a 
  quiescent 
  state 
  for 
  even 
  a 
  year 
  or 
  more, 
  and 
  afterwards, 
  by 
  

   allowing 
  warmth 
  to 
  come 
  to 
  them, 
  they 
  could 
  be 
  developed 
  

   into 
  the 
  perfect 
  snail. 
  That 
  to 
  a 
  certain 
  extent 
  the 
  retard- 
  

   ing 
  of 
  tlie 
  development 
  can 
  be 
  made 
  available 
  with 
  fish 
  

   spawn, 
  is 
  undoubtedty 
  the 
  experience 
  of 
  every 
  piscicul- 
  

   turist, 
  but 
  just 
  to 
  what 
  limits 
  it 
  is 
  best 
  to 
  retard 
  or 
  Ibrce 
  

   the 
  growth 
  of 
  th.e 
  young 
  embryo, 
  is 
  a 
  question 
  worthy 
  

   of 
  more 
  study 
  than 
  it 
  has 
  yet 
  received.^ 
  If 
  the 
  temperature 
  

   is 
  too 
  low 
  they 
  will 
  be 
  too 
  long 
  developing 
  ; 
  if 
  too 
  high 
  

   they 
  Avill 
  be 
  apt 
  to 
  be 
  too 
  delicate 
  to 
  survive 
  in 
  any 
  water 
  

   into 
  which 
  tliey 
  may 
  be 
  trans})lanted. 
  From 
  the 
  20th 
  of 
  

   March 
  on, 
  the 
  hydrant 
  water 
  rose 
  steadily 
  in 
  temperature 
  

   until 
  the 
  young 
  fish 
  were 
  all 
  hatched 
  and 
  transported 
  to 
  

   their 
  final 
  homes 
  in 
  the 
  waters 
  of 
  Maryland. 
  This 
  rise 
  of 
  

   temperature 
  was 
  from 
  37° 
  up 
  to 
  50°, 
  or 
  a 
  difference 
  of 
  13°. 
  

   The 
  experience 
  of 
  this 
  year's 
  work 
  with 
  the 
  smelt 
  would 
  

   seem 
  to 
  indicate 
  that 
  the 
  spawn 
  thrives 
  best 
  in 
  water 
  of 
  a 
  

   temperature 
  from 
  40° 
  upward, 
  or 
  perhaps 
  I 
  might 
  say, 
  in 
  

   water 
  of 
  an 
  average 
  temperature 
  of 
  44°. 
  , 
  

  

  Spawn 
  taken 
  and 
  placed 
  in 
  water 
  of 
  this 
  temperature 
  

   would 
  undoubtedly 
  hatch 
  cut 
  in 
  from 
  three 
  to 
  four 
  weeks, 
  

  

  iSee 
  an 
  address 
  upon 
  the 
  artificial 
  breeding 
  of 
  fisbes, 
  read 
  before 
  the 
  

   Detroit 
  Scientific 
  Association 
  by 
  Mr. 
  N. 
  W. 
  Claric, 
  page 
  9, 
  et 
  scq. 
  

  

  