﻿Siphonophora 
  of 
  the 
  Canary 
  Islands. 
  219 
  

  

  organ-theory 
  and 
  the 
  polyperson-theory, 
  he 
  regards 
  the 
  larva 
  

   of 
  the 
  Siphonophora 
  as 
  a 
  Medusa 
  with 
  dislocated 
  organs 
  and 
  

   assumes 
  in 
  the 
  developed 
  stocks 
  a 
  profound 
  secondary 
  dislo- 
  

   cation 
  of 
  the 
  different 
  constituents 
  of 
  the 
  Medusa. 
  Hackel's 
  

   results 
  so 
  nearly 
  approach 
  the 
  views 
  of 
  Metschnikoff*, 
  who 
  

   interpreted 
  the 
  Siphonophoran 
  larva 
  in 
  the 
  same 
  way, 
  and 
  

   who 
  likewise 
  compared 
  the 
  developed 
  colony 
  to 
  a 
  Sarsia 
  with 
  

   the 
  stomach 
  grown 
  out 
  into 
  a 
  peduncular 
  form 
  and 
  gemmi- 
  

   parous, 
  that 
  1 
  must 
  once 
  more 
  adduce 
  all 
  the 
  difficulties 
  which 
  

   Leuckart 
  t> 
  and 
  subsequently 
  Clans, 
  raised 
  against 
  the 
  views 
  

   of 
  Metschnikoff 
  and 
  P. 
  E. 
  Miiller. 
  Even 
  now, 
  when 
  we 
  

   possess 
  a 
  sufficient 
  knowledge 
  of 
  the 
  polymorphous 
  Medusae 
  and 
  

   their 
  processes 
  of 
  gemmation, 
  there 
  is 
  nothing 
  to 
  support 
  the 
  

   notion 
  of 
  a 
  dislocation. 
  So 
  long 
  as 
  we 
  have 
  no 
  demonstration 
  

   that 
  nectocalyx, 
  stomachal 
  tube, 
  tentacles, 
  and 
  bract 
  (hydro- 
  

   phyllium) 
  are 
  produced 
  by 
  dislocation 
  from 
  a 
  single 
  bud, 
  so 
  long- 
  

   as 
  the 
  difficulty 
  is 
  not 
  got 
  rid 
  of 
  that, 
  on 
  the 
  other 
  hand, 
  three 
  

   or 
  four 
  separate 
  buds, 
  originally 
  quite 
  similar, 
  concur 
  in 
  the 
  

   formation 
  of 
  a 
  monogastric 
  Siphonophoran, 
  which, 
  in 
  toto, 
  is 
  

   homologous 
  with 
  a 
  Medusa, 
  I 
  must 
  decline 
  to 
  admit 
  the 
  as- 
  

   sumption 
  of 
  such 
  a 
  dislocation. 
  On 
  the 
  contrary, 
  when 
  rudi- 
  

   ments 
  of 
  tentacles, 
  marginal 
  corpuscles, 
  and 
  manubria 
  make 
  

   their 
  appearance 
  on 
  the 
  nectocalyces 
  of 
  the 
  Siphonophora, 
  we 
  

   always 
  see 
  them 
  indicated 
  upon 
  the 
  ordinary 
  spots. 
  How 
  

   such 
  rudiments, 
  which 
  are 
  observed 
  especially 
  upon 
  the 
  

   nectocalyces 
  of 
  the 
  genus 
  Lilyopsis, 
  established 
  by 
  me, 
  can 
  

   be 
  brought 
  into 
  accordance 
  with 
  dislocation 
  completed 
  at 
  the 
  

   same 
  time, 
  is 
  to 
  me 
  just 
  as 
  incomprehensible 
  as 
  Hackel's 
  and 
  

   Metschnikoff's 
  supposition 
  that 
  the 
  value 
  of 
  individualities 
  

   belongs 
  only 
  to 
  the 
  genital 
  nectocalyces 
  and 
  the 
  recently 
  

   demonstrated 
  " 
  aurophores." 
  The 
  genital 
  calyces 
  themselves 
  

   present 
  such 
  profound 
  retrogressions 
  that, 
  in 
  the 
  form 
  of 
  

   sporosacs, 
  they 
  left 
  Weismann 
  in 
  doubt 
  whether 
  we 
  have 
  

   here 
  to 
  do 
  with 
  retrograde 
  Medusa? 
  or 
  Polypes. 
  We 
  never 
  

   observe 
  such 
  far-reaching 
  reductions 
  in 
  the 
  locomotive 
  

   elements, 
  which 
  always 
  show 
  their 
  velum, 
  the 
  fine 
  muscula- 
  

   ture 
  of 
  the 
  subumbrella, 
  the 
  ordinary 
  course 
  of 
  the 
  vessels, 
  

   and 
  in 
  all 
  cases 
  a 
  nerve-ring 
  at 
  the 
  margin 
  of 
  the 
  umbrella, 
  

   as 
  I 
  have 
  been 
  able 
  to 
  demonstrate 
  in 
  all 
  the 
  calyces 
  (most 
  

   distinctly 
  developed 
  in 
  the 
  species 
  of 
  Abyla). 
  

  

  To 
  what 
  inconsistencies 
  Hackel's 
  views 
  lead 
  may 
  be 
  further 
  

  

  * 
  ' 
  Verhandlungen 
  der 
  Gesellsch. 
  fur 
  Naturk.' 
  (Moscow), 
  vol. 
  viii. 
  

   1870 
  (in 
  Russian), 
  and, 
  further, 
  Zeitscbr. 
  fiir 
  wiss. 
  Zool. 
  Bd. 
  xxiv. 
  (1871), 
  

   pp. 
  05-77. 
  

  

  t 
  " 
  Bericht 
  &c," 
  in 
  Arch, 
  fur 
  Naturg. 
  Jahrg. 
  xl. 
  (1874) 
  ii. 
  pp. 
  183- 
  

   184, 
  and 
  Jahrg. 
  xli. 
  (1875) 
  ii. 
  pp. 
  452-459. 
  

  

  