﻿64 
  Miscellaneous. 
  

  

  The 
  above 
  is 
  a 
  very 
  imperfect 
  account 
  of 
  a 
  most 
  interesting 
  

   treatise 
  ; 
  but 
  the 
  fact 
  is 
  that 
  in 
  order 
  to 
  do 
  more 
  it 
  would 
  have 
  been 
  

   necessary 
  to 
  translate 
  almost 
  the 
  whole 
  work. 
  We 
  may 
  add 
  that 
  

   it 
  is 
  written 
  in 
  German 
  and 
  that 
  the 
  plates 
  furnish 
  greatly 
  enlarged 
  

   figures 
  of 
  the 
  characteristic 
  parts 
  of 
  the 
  animals 
  described. 
  

  

  MISCELLANEOUS. 
  

  

  Preliminary 
  Note 
  on 
  the 
  Functions 
  and 
  Homologies 
  of 
  the 
  Contractile 
  

   Vacuole 
  in 
  Plants 
  and 
  Animals. 
  By 
  Professor 
  Marcus 
  M. 
  Har- 
  

   tog, 
  D.Sc, 
  M.A 
  * 
  

  

  Through 
  the 
  practice 
  of 
  regarding 
  botany 
  and 
  zoology 
  as 
  essen- 
  

   tially 
  distinct 
  studies 
  the 
  solution 
  of 
  many 
  an 
  interesting 
  problem 
  

   in 
  the 
  one 
  domain 
  is 
  long 
  missed, 
  because 
  the 
  known 
  facts 
  that 
  

   afford 
  a 
  clue 
  when 
  properly 
  applied 
  have 
  been 
  worked 
  out 
  only 
  in 
  

   the 
  other, 
  and 
  are 
  contained 
  in 
  records 
  never 
  likely 
  to 
  be 
  consulted 
  

   in 
  reference 
  to 
  the 
  given 
  problem. 
  Thus 
  the 
  " 
  contractile 
  vacuole 
  " 
  

   is 
  an 
  organ 
  that 
  exists 
  in 
  both 
  kingdoms 
  : 
  the 
  question 
  of 
  proto- 
  

   plasmic 
  vacuolation, 
  of 
  which 
  this 
  is 
  a 
  particular 
  case, 
  has 
  only 
  been 
  

   really 
  studied 
  by 
  the 
  vegetable 
  physiologist, 
  and 
  yet 
  in 
  the 
  minute 
  

   plant-cells 
  which 
  possess 
  this 
  organ 
  it 
  is 
  too 
  small 
  for 
  the 
  study 
  of 
  

   the 
  mechanism 
  of 
  its 
  work 
  ; 
  this 
  study 
  has 
  been 
  successfully 
  carried 
  

   out 
  by 
  zoologists 
  on 
  the 
  larger 
  Ciliata 
  and 
  Heliozoa, 
  in 
  ignorance, 
  

   however, 
  of 
  the 
  known 
  facts 
  that 
  explained 
  the 
  reason 
  of 
  its 
  working. 
  

   Thus 
  the 
  botanists 
  had 
  forged 
  a 
  key 
  of 
  the 
  right 
  pattern, 
  but 
  too 
  

   big 
  to 
  open 
  the 
  locks 
  in 
  their 
  own 
  domain, 
  while 
  fitting 
  that 
  of 
  

   which 
  the 
  zoologists 
  had 
  described 
  the 
  wards 
  and 
  tumblers. 
  In 
  

   this 
  preliminary 
  communication 
  I 
  shall 
  only 
  put 
  the 
  key 
  into 
  the 
  

   lock, 
  reserving 
  original 
  observations 
  for 
  a 
  complete 
  paper. 
  

  

  I. 
  Distribution. 
  — 
  One 
  or 
  more 
  contractile 
  vacuoles 
  occur 
  in 
  all 
  

   naked 
  plant-zoospores, 
  with 
  scarcely 
  a 
  recorded 
  exception, 
  whether 
  

   mastigopod 
  or 
  myxopod, 
  whether 
  Algal, 
  Fungal 
  (Saprolegnieae, 
  

   Peronosporese, 
  Chytridiese), 
  or 
  Myxomycete. 
  They 
  occur 
  in 
  all 
  

   freshwater 
  Protozoa 
  when 
  in 
  the 
  active 
  state, 
  though 
  not 
  when 
  

   encysted 
  ; 
  they 
  are, 
  however, 
  absent 
  from 
  many 
  of 
  those 
  that 
  live 
  in 
  

   the 
  perivisceral 
  fluid 
  or 
  blood 
  of 
  living 
  hosts 
  and 
  from 
  the 
  Padiolaria 
  

   and 
  possibly 
  other 
  marine 
  forms. 
  

  

  II. 
  Position 
  and 
  Mechanism. 
  — 
  They 
  are 
  vacuoles 
  in 
  the 
  proto- 
  

   plasm, 
  usually 
  peripheral 
  ; 
  they 
  contract 
  to 
  disappearance 
  at 
  regular 
  

   intervals 
  ; 
  in 
  favourable 
  cases 
  (ActinosjjJuvrium, 
  many 
  Ciliata) 
  

   they 
  are 
  seen 
  on 
  contraction 
  to 
  discharge 
  their 
  contents 
  into 
  the 
  

   water. 
  In 
  a 
  few 
  cases 
  they 
  are 
  known 
  to 
  be 
  reservoirs 
  filled 
  

   gradually 
  by 
  the 
  almost 
  continuous 
  influx 
  from 
  plasmatic 
  canals, 
  

   which 
  are 
  invisible 
  from 
  this 
  very 
  reason, 
  only 
  starting 
  into 
  sight 
  

  

  * 
  Read 
  at 
  the 
  British 
  Association 
  (Bath), 
  1888. 
  

  

  