﻿VI 
  CONTENTS 
  

  

  Page 
  

  

  What 
  is 
  light? 
  by 
  Arthur 
  H. 
  Compton 
  215 
  

  

  Artificial 
  cold, 
  by 
  Gordon 
  B. 
  Wilkes 
  229 
  

  

  Photosynthesis, 
  by 
  E. 
  C. 
  C. 
  Baly 
  237 
  

  

  Newly 
  discovered 
  chemical 
  elements, 
  by 
  N. 
  M. 
  Bligh 
  245 
  

  

  Synthetic 
  perfumes, 
  by 
  H. 
  Stanley 
  Redgrove 
  253 
  

  

  X-raying 
  the 
  earth, 
  by 
  Reginald 
  A. 
  Daly 
  261 
  

  

  Extinction 
  and 
  extermination, 
  by 
  I. 
  P. 
  TolmachofT 
  269 
  

  

  The 
  Gulf 
  Stream 
  and 
  its 
  problems, 
  by 
  PI. 
  A. 
  Marmer 
  285 
  

  

  The 
  mystery 
  of 
  life, 
  by 
  F. 
  G. 
  Donnan 
  309 
  

  

  The 
  transition 
  from 
  live 
  to 
  dead: 
  the 
  nature 
  of 
  filtrable 
  viruses, 
  by 
  A. 
  E. 
  

  

  Boycott 
  323 
  

  

  Heritable 
  variations, 
  their 
  production 
  by 
  X 
  rays, 
  and 
  their 
  relation 
  to 
  

  

  evolution, 
  by 
  H. 
  J. 
  Muller 
  345 
  

  

  Social 
  parasitism 
  in 
  birds, 
  by 
  Herbert 
  Friedmann 
  363 
  

  

  How 
  insects 
  fly, 
  by 
  R. 
  E. 
  Snodgrass 
  383 
  

  

  Climate 
  and 
  migrations, 
  by 
  J. 
  C. 
  Curry 
  423 
  

  

  Ur 
  of 
  the 
  Chaldees: 
  more 
  royal 
  tombs, 
  by 
  C. 
  Leonard 
  Woolley 
  437 
  

  

  The 
  population 
  of 
  ancient 
  America, 
  by 
  H. 
  J. 
  Spinden 
  451 
  

  

  The 
  aborigines 
  of 
  the 
  ancient 
  island 
  of 
  Hispaniola, 
  by 
  Herbert 
  W. 
  Krieger_ 
  473 
  

   The 
  beginning 
  of 
  the 
  mechanical 
  transport 
  era 
  in 
  America, 
  by 
  Carl 
  W. 
  

  

  Mitman 
  507 
  

  

  The 
  servant 
  in 
  the 
  house; 
  a 
  brief 
  historj^ 
  of 
  the 
  sewing 
  machine, 
  by 
  Fred- 
  

   erick 
  L. 
  Lewton 
  559 
  

  

  Thomas 
  Chrowdcr 
  Chamberlin 
  (1843-1928) 
  , 
  by 
  Bailey 
  Willis 
  585 
  

  

  Hideyo 
  Noguchi, 
  by 
  Simon 
  Flexner 
  595 
  

  

  