﻿THE 
  ANATOMY 
  OF 
  FCECILOOH^TUS, 
  OLAPAK'EDB. 
  127 
  

  

  podia, 
  whilst 
  the 
  Literal 
  vessels 
  of 
  segments 
  8, 
  9, 
  10 
  and 
  11 
  

   arise 
  close 
  together 
  about 
  the 
  level 
  of 
  the 
  twelfth 
  parapodia. 
  

   On 
  reaching 
  the 
  base 
  of 
  the 
  parapodium 
  of 
  the 
  segment 
  to 
  

   which 
  it 
  belongs, 
  the 
  lateral 
  blood-vessel 
  in 
  each 
  case 
  leaves 
  

   the 
  septum 
  and 
  sends 
  a 
  loop 
  forwards 
  into 
  the 
  parapodium, 
  

   the 
  loop 
  returning 
  upon 
  itself 
  and 
  joiuuigthe 
  septum 
  again 
  in 
  

   the 
  neighbourhood 
  of 
  the 
  internal 
  opening 
  of 
  the 
  nephridium. 
  

   The 
  vessel 
  here 
  divides 
  into 
  two 
  branches. 
  One 
  of 
  these 
  

   branches 
  passes 
  downwards 
  and 
  inwards 
  and 
  opens 
  directly 
  

   into 
  the 
  large 
  longitudinal 
  ventral 
  blood-vessel, 
  the 
  other 
  

   passes 
  through 
  the 
  septum 
  close 
  to 
  the 
  tube 
  of 
  the 
  

   nephridium, 
  and 
  in 
  the 
  segment 
  behind 
  divides 
  up 
  into 
  a 
  

   number 
  of 
  blind, 
  finger-shaped 
  processes, 
  which 
  spread 
  out 
  in 
  

   the 
  body-cavitj'" 
  of 
  that 
  segment. 
  Under 
  favourable 
  circum- 
  

   stances 
  these 
  finger-shaped 
  processes 
  can 
  be 
  seen 
  iu 
  the 
  

   living 
  worm, 
  alternately 
  expanding 
  and 
  contracting 
  as 
  they 
  

   till 
  with 
  the 
  bright 
  red 
  blood 
  and 
  empty 
  themselves 
  again. 
  

   On 
  one 
  occasion, 
  in 
  a 
  worm 
  the 
  body-wall 
  of 
  which 
  had 
  burst 
  

   on 
  compression, 
  I 
  was 
  fortunate 
  enough 
  to 
  see 
  one 
  of 
  these 
  

   clusters 
  of 
  finger-shaped 
  vessels 
  lying 
  outside 
  the 
  body 
  and 
  

   to 
  satisfy 
  myself 
  that 
  each 
  process 
  visible 
  ended 
  blindly. 
  

   The 
  vessels 
  when 
  filled 
  with 
  blood 
  are 
  very 
  conspicuous, 
  and 
  

   easily 
  followed 
  in 
  sections 
  (PI. 
  11, 
  figs. 
  48 
  and 
  49), 
  and 
  in 
  

   spite 
  of 
  repeated 
  attempts 
  I 
  have 
  never 
  been 
  able 
  to 
  find 
  that 
  

   this 
  cluster 
  of 
  vessels 
  has 
  any 
  communication 
  with 
  the 
  rest 
  

   of 
  the 
  blood 
  system, 
  excepting 
  through 
  the 
  branch 
  of 
  the 
  

   lateral 
  vessel 
  of 
  the 
  segment 
  in 
  front, 
  which 
  accompanies 
  the 
  

   nephridial 
  tube 
  thi'ough 
  the 
  septum 
  dividing 
  the 
  two 
  seguients. 
  

   Fig. 
  51 
  (Pi. 
  12), 
  drawn 
  from 
  a 
  longitudinal 
  vertical 
  section, 
  

   shows 
  clearly 
  the 
  branch 
  of 
  the 
  lateral 
  vessel 
  {h. 
  kit. 
  v.) 
  

   passing 
  back 
  through 
  the 
  septum 
  into 
  the 
  segment 
  behind 
  and 
  

   there 
  breaking 
  up 
  into 
  finger-shaped 
  processes 
  (/. 
  p-)- 
  Fig. 
  49 
  

   (PI. 
  11) 
  represents 
  a 
  transverse 
  section 
  through 
  the 
  finger- 
  

   shaped 
  processes 
  (f.p.), 
  and 
  shows 
  the 
  great 
  enlargement 
  of 
  the 
  

   blood-vessel 
  which 
  can 
  take 
  place 
  at 
  the 
  point 
  where 
  the 
  pro- 
  

   cesses 
  are 
  given 
  off. 
  Pig. 
  48 
  (PI. 
  11) 
  shows 
  well 
  the 
  latter 
  part 
  

   of 
  the 
  course 
  of 
  the 
  lateral 
  vessels 
  {lat. 
  v.) 
  to 
  the 
  ventral 
  vessel. 
  

  

  