﻿498 
  Mr. 
  L. 
  Tait 
  on 
  the 
  [June 
  17, 
  

  

  made 
  in 
  two 
  halves, 
  a 
  groove 
  of 
  a 
  zigzag 
  form 
  being 
  cast 
  in 
  each 
  half, 
  

   so 
  that 
  when 
  the 
  two 
  are 
  screwed 
  together 
  a 
  continuous 
  channel 
  is 
  main- 
  

   taiued 
  through 
  the 
  bearings 
  for 
  a 
  current 
  of 
  cold 
  water 
  to 
  pass 
  during 
  

   the 
  whole 
  time 
  the 
  machine 
  is 
  at 
  work. 
  

  

  The 
  advantages 
  suggested 
  by 
  these 
  arrangements 
  are 
  their 
  extreme 
  

   simplicity, 
  the 
  few 
  number 
  of 
  parts, 
  only 
  one 
  armature 
  and 
  one 
  wire 
  

   being 
  used. 
  

  

  This 
  principle 
  of 
  the 
  alternate 
  current 
  being 
  utilized 
  is 
  also 
  applicable 
  

   to 
  machines 
  constructed 
  on 
  the 
  multiple 
  armature 
  principle; 
  and 
  the 
  

   economy 
  thereby 
  resulting 
  would 
  prove 
  of 
  great 
  advantage, 
  as 
  the 
  power 
  

   of 
  the 
  machine 
  could 
  be 
  varied 
  by 
  throwing 
  into 
  the 
  electromagnets 
  

   either 
  every 
  other 
  current, 
  or 
  every 
  fourth, 
  sixth, 
  or 
  eighth 
  current, 
  

   according 
  to 
  the 
  strength 
  required 
  in 
  the 
  machine, 
  the 
  whole 
  of 
  the 
  other 
  

   currents 
  being 
  utilized 
  for 
  electric 
  light 
  or 
  otherwise. 
  

  

  II. 
  " 
  Note 
  on 
  the 
  Anatomy 
  of 
  the 
  Umbilical 
  Cord." 
  By 
  Lawson 
  

   Tait, 
  F.R.C.S. 
  Communicated 
  by 
  W. 
  S. 
  Savory, 
  F.R.S. 
  

   Received 
  April 
  28, 
  1875. 
  

  

  (Abstract.) 
  

  

  I. 
  Its 
  external 
  form 
  and 
  method 
  of 
  growth. 
  

   II. 
  Its 
  covering. 
  

  

  III. 
  Its 
  substance. 
  

  

  IV. 
  Its 
  vessels. 
  

  

  V. 
  Its 
  relations 
  to 
  the 
  foetus 
  and 
  placenta. 
  

   VI. 
  Its 
  nutrition. 
  

  

  I. 
  The 
  spiral 
  form 
  of 
  the 
  cord 
  has 
  received 
  many 
  explanations 
  ; 
  but 
  

   hitherto 
  none 
  has 
  seemed 
  satisfactory, 
  nor 
  sufficient 
  to 
  explain 
  all 
  the 
  facts. 
  

   The 
  cause 
  of 
  the 
  spiral 
  form 
  has 
  generally 
  been 
  regarded 
  as 
  existing 
  in 
  

   the 
  arteries 
  ; 
  but 
  experiment 
  shows 
  that 
  the 
  vein 
  is 
  the 
  chief 
  factor. 
  

  

  The 
  considerations 
  drawn 
  from 
  the 
  comparative 
  and 
  teratological 
  ana- 
  

   tomy 
  of 
  the 
  cord 
  point 
  to 
  the 
  conclusion 
  that 
  its 
  twist 
  must 
  depend 
  upon 
  

   some 
  mechanism 
  at 
  the 
  foetal 
  insertion. 
  

  

  Such 
  mechanism 
  is 
  found 
  in 
  a 
  peculiar 
  camb-like 
  growth 
  of 
  the 
  dermal 
  

   ring 
  of 
  the 
  umbilicus, 
  and 
  in 
  an 
  arrangement 
  of 
  capillaries 
  upon 
  which 
  

   the 
  nutrition 
  of 
  the 
  cord 
  depends, 
  that 
  nutrition 
  being 
  supplied 
  over 
  the 
  

   venous 
  surface 
  of 
  the 
  cord 
  in 
  about 
  the 
  proportion 
  of 
  three 
  to 
  two 
  on 
  

   the 
  arterial 
  surface. 
  This 
  unequal 
  nutrition 
  would 
  seem 
  necessarily 
  to 
  

   result 
  in 
  a 
  spiral. 
  

  

  II. 
  When 
  the 
  surface 
  of 
  the 
  cord 
  is 
  treated 
  with 
  litmus 
  or 
  haeina- 
  

   toxylin, 
  the 
  epithelial 
  covering 
  is 
  found 
  to 
  consist 
  of 
  a 
  single 
  layer 
  

   of 
  irregularly 
  polygonal 
  cells, 
  regularly 
  nucleated. 
  The 
  fibrillar 
  matrix 
  

   on 
  which 
  they 
  lie 
  is 
  evidently 
  only 
  a 
  slightly 
  condensed 
  arrangement 
  of 
  

   the 
  canalicular 
  tissue. 
  Silver-staining 
  shows 
  that 
  these 
  cells 
  have 
  a 
  

   peculiar 
  irregularity 
  in 
  size 
  and 
  arrangement. 
  - 
  

  

  