﻿148 
  Mr. 
  J. 
  Gray. 
  

  

  Table 
  It 
  

  

  Cone, 
  of 
  La 
  (N0 
  3 
  ) 
  3 
  . 
  

  

  Relative 
  Charge. 
  

  

  

  

  -60 
  

  

  0-0O004Mol. 
  

  

  -58 
  

  

  -0002 
  „ 
  

  

  -18 
  

  

  -ooi 
  

  

  - 
  1 
  

  

  These 
  results 
  have 
  been 
  confirmed 
  and 
  enlarged 
  by 
  Mines 
  (9) 
  and 
  10). 
  

   This 
  author 
  applied 
  the 
  name 
  of 
  " 
  polarising 
  ions 
  " 
  to 
  those 
  ions 
  which 
  are 
  

   capable 
  of 
  affecting 
  the 
  surface 
  charge 
  of 
  a 
  membrane 
  or 
  particle 
  to 
  any 
  

   marked 
  degree. 
  Such 
  ions 
  are 
  the 
  hydrogen 
  ion, 
  hydroxyl 
  ion, 
  and 
  such 
  

   trivalent 
  ions 
  as 
  cerium, 
  lanthanum, 
  and 
  the 
  citrate 
  ion. 
  

  

  Finally, 
  the 
  work 
  of 
  Chick 
  and 
  Martin 
  (2) 
  on 
  the 
  precipitation 
  of 
  albumen 
  

   or 
  globulin 
  suspensions 
  by 
  such 
  salts 
  as 
  lanthanum 
  is 
  of 
  great 
  interest. 
  

   These 
  authors 
  show 
  clearly 
  that 
  the 
  precipitating 
  power 
  of 
  such 
  salts 
  as 
  

   lanthanum 
  nitrate 
  or 
  sodium 
  citrate 
  depends 
  very 
  closely 
  upon 
  the 
  hydroxyl 
  

   ion 
  concentration 
  of 
  the 
  colloid 
  suspension. 
  If 
  albumen 
  is 
  dissolved 
  in 
  

   dilute 
  acid, 
  lanthanum 
  salts 
  do 
  not 
  precipitate 
  the 
  colloid 
  ; 
  these 
  salts 
  are, 
  

   however, 
  powerful 
  precipitants 
  from 
  an 
  alkaline 
  medium. 
  They 
  have 
  also 
  

   shown 
  that 
  lanthanum 
  is 
  capable 
  of 
  conveying 
  a 
  positive 
  charge 
  to 
  such 
  

   particles 
  if 
  the 
  salt 
  is 
  sufficiently 
  concentrated. 
  Precipitation 
  only 
  occurs 
  

   when 
  the 
  " 
  polarising 
  " 
  elements 
  present 
  allow 
  the 
  particles 
  to 
  possess 
  a 
  

   minimum 
  charge. 
  In 
  other 
  words, 
  precipitation 
  occurs 
  at 
  the 
  isoelectric 
  

   point. 
  

  

  The 
  application 
  of 
  these 
  principles 
  to 
  physiology 
  was 
  first 
  made 
  by 
  

   Mines, 
  who 
  investigated 
  the 
  relationship 
  of 
  the 
  vertebrate 
  heart 
  to 
  

   polarising 
  and 
  other 
  ions. 
  He 
  also 
  showed 
  that 
  red-blood 
  corpuscles 
  

   suspended 
  in 
  Einger 
  solution 
  closely 
  resemble 
  the 
  negative 
  particles 
  of 
  an 
  

   emulsoid 
  colloid. 
  

  

  In 
  1916 
  the 
  writer 
  (7) 
  described 
  the 
  effects 
  of 
  lanthanum 
  or 
  cerium 
  upon 
  

   the 
  electrical 
  conductivity 
  of 
  echinoderm 
  eggs, 
  and 
  reference 
  was 
  made 
  to 
  

   the 
  possibility 
  that 
  the 
  nature 
  of 
  the 
  surface 
  charge 
  on 
  the 
  egg 
  played 
  an 
  

   important 
  role, 
  in 
  the 
  phenomena 
  of 
  artificial 
  parthenogenesis. 
  The 
  present 
  

   experiments 
  with 
  the 
  spermatozoa 
  of 
  Echinus 
  miliaris 
  form 
  an 
  attempt 
  to 
  

   attack 
  the 
  problem 
  of 
  fertilisation 
  from 
  a 
  similar 
  standpoint. 
  

  

  At 
  the 
  outset 
  it 
  is 
  convenient 
  to 
  refer 
  to 
  one 
  or 
  two 
  well-known 
  facts. 
  In 
  

   the 
  first 
  place, 
  spermatozoa 
  suspended 
  in 
  sea 
  water 
  are 
  surrounded 
  by 
  an 
  

   alkaline 
  medium 
  whose 
  P 
  H 
  is 
  about 
  8 
  - 
  0. 
  In 
  the 
  second 
  place, 
  the 
  interior 
  of 
  

   the 
  living 
  cell 
  is 
  always 
  more 
  acid 
  than 
  the 
  surrounding 
  medium. 
  Living 
  

  

  