﻿150 
  

  

  Mr. 
  J. 
  Gray. 
  

  

  alkaline 
  solutions 
  ; 
  the 
  phenomena 
  observed 
  are 
  the 
  same 
  in 
  the 
  two 
  cases 
  

   and 
  are 
  capable 
  of 
  the 
  same 
  explanation. 
  

  

  In 
  the 
  presence 
  of 
  cerium 
  or 
  lanthanum 
  the 
  negative 
  charge 
  on 
  the 
  surface 
  

   of 
  the 
  cell 
  or 
  the 
  particle 
  is 
  lost 
  and 
  agglutination 
  results. 
  In 
  the 
  presence 
  

   of 
  citrate, 
  however, 
  the 
  negative 
  charge 
  is 
  restored 
  by 
  the 
  negative 
  trivalent 
  

   ion, 
  and 
  dispersal 
  consequently 
  takes 
  place. 
  

  

  That 
  the 
  agglutination 
  caused 
  by 
  cerium 
  or 
  lanthanum 
  is 
  completely 
  

   reversible 
  by 
  sodium 
  citrate 
  is 
  illustrated 
  by 
  the 
  following 
  experiment 
  : 
  

   100 
  c.c. 
  of 
  sperm 
  suspension 
  was 
  agglutinated 
  by 
  means 
  of 
  cerium 
  and 
  the 
  

   spermatozoa 
  washed 
  in 
  several 
  changes 
  of 
  sea 
  water 
  ; 
  10 
  c.c. 
  of 
  this 
  

   agglutinated 
  suspension 
  were 
  placed 
  in 
  several 
  test-tubes 
  to 
  which 
  varying 
  

   amounts 
  of 
  - 
  8 
  M 
  sodium 
  citrate 
  solution 
  were 
  added. 
  The 
  tubes 
  were- 
  

   gently 
  and 
  uniformly 
  shaken 
  : 
  — 
  

  

  Table 
  IV. 
  

  

  Amount 
  of 
  citrate 
  added 
  

   to 
  10 
  c.c. 
  suspension. 
  

  

  Ph. 
  

  

  Agglutination 
  after 
  

   15 
  min. 
  

  

  c.c. 
  

  

  

  

  

  

  7-9 
  

  

  + 
  + 
  + 
  

  

  0-5 
  

  

  7-95 
  

  

  + 
  

  

  1 
  

  

  8-0 
  

  

  © 
  

  

  1 
  -5 
  

  

  8-1 
  

  

  © 
  

  

  2-0 
  

  

  8-2 
  

  

  

  

  2-5 
  

  

  8-3 
  

  

  

  

  3 
  

  

  8-4 
  

  

  

  

  4 
  -0 
  

  

  8-5 
  

  

  

  

  02 
  04 
  06 
  0B 
  10 
  12 
  -14 
  -16 
  

  

  Molecular 
  Cone, 
  of 
  Ala, 
  Cir 
  in 
  Sea 
  -Water, 
  

  

  Diagram 
  showing 
  Removal 
  of 
  Cerium 
  Precipitation 
  by 
  Sodium 
  Citrate. 
  

  

  