﻿116 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  important 
  remedy 
  and 
  to 
  be 
  much 
  superior 
  to 
  other 
  fats 
  for 
  this 
  

   purpose. 
  In 
  1890 
  Palm, 
  observing 
  that 
  rickets 
  was 
  more 
  prevalent 
  

   in 
  the 
  Temperate 
  Zones 
  than 
  in 
  the 
  Tropics, 
  and 
  that 
  there 
  appeared 
  

   to 
  be 
  seasonal 
  variations, 
  attributed 
  this 
  to 
  the 
  influence 
  of 
  sunlight. 
  

   However, 
  for 
  many 
  years 
  thereafter 
  little 
  attention 
  was 
  paid 
  to 
  

   Palm's 
  work, 
  and 
  the 
  relation 
  of 
  light 
  to 
  rickets 
  was 
  considered 
  inci- 
  

   dental. 
  In 
  1919, 
  however, 
  Huldchinsky, 
  working 
  with 
  undernour- 
  

   ished 
  children 
  in 
  Vienna 
  following 
  the 
  war, 
  found 
  that 
  rickets 
  could 
  

   be 
  cured 
  by 
  exposure 
  of 
  the 
  affected 
  child 
  to 
  ultraviolet 
  light 
  from 
  a 
  

   mercury 
  arc. 
  This 
  surprising 
  result 
  was 
  soon 
  confirmed 
  by 
  work- 
  

   ers 
  in 
  various 
  parts 
  of 
  the 
  world, 
  notably 
  by 
  Hess 
  and 
  his 
  asso- 
  

   ciates. 
  This 
  discovery 
  that 
  exposure 
  of 
  a 
  child 
  to 
  light 
  could 
  com- 
  

  

  5050 
  A 
  

  

  H- 
  

  

  ZY 
  --- 
  ' 
  ' 
  X 
  -x_./"'° 
  "'"--•—.. 
  / 
  

  

  c> 
  

  

  3II0A 
  

  

  

  15 
  £0 
  25 
  30 
  

  

  JUNE, 
  1940 
  

  

  Figure 
  4. 
  — 
  Daily 
  variations 
  in 
  quantity 
  of 
  atmospheric 
  ozone. 
  

  

  pensate 
  for 
  a 
  deficiency 
  in 
  diet 
  was 
  of 
  great 
  significance. 
  Closer 
  

   attention 
  was 
  directed 
  to 
  the 
  fats, 
  and 
  in 
  1924 
  Steenbock 
  and, 
  inde- 
  

   pendently, 
  Hess 
  reported 
  that 
  fats 
  and 
  oils 
  which 
  were 
  not 
  curative 
  

   in 
  rickets 
  could 
  be 
  rendered 
  potent 
  by 
  exposure 
  to 
  ultraviolet 
  light. 
  

   It 
  became 
  evident 
  that 
  the 
  active 
  principle, 
  or 
  vitamin 
  D 
  as 
  it 
  was 
  

   called, 
  was 
  being 
  formed 
  from 
  some 
  provitamin 
  by 
  the 
  action 
  of 
  

   light. 
  Numerous 
  investigations 
  by 
  Hess 
  and 
  his 
  associates, 
  by 
  Rosen- 
  

   heim 
  and 
  Webster, 
  by 
  Windaus, 
  and 
  by 
  others 
  too 
  numerous 
  to 
  men- 
  

   tion 
  here, 
  demonstrated 
  that 
  ergosterol, 
  first 
  isolated 
  by 
  Tanret 
  in 
  

   1889, 
  is 
  a 
  parent 
  substance 
  from 
  which 
  vitamin 
  D 
  is 
  produced 
  by 
  

   ultraviolet 
  radiation. 
  

  

  At 
  first 
  it 
  appeared 
  that 
  only 
  from 
  ergosterol 
  could 
  vitamin 
  D 
  be 
  

   formed. 
  However, 
  discrepancies 
  were 
  soon 
  noted 
  in 
  the 
  vitamin-D 
  

   potency 
  of 
  irradiated 
  preparations 
  when 
  tested 
  on 
  birds 
  (usually 
  the 
  

  

  