div class=ts-pagebuttonPage 1button div class=ts-image amp-img class=ts-thumb alt=Page 1: Dr Arthur L Day src=https:reader030vdocumentsinreader030viewer2022020223575067e31a28ab0f07ad9b51html5thumbnails1jpg width=142 height=106 layout=responsive amp-img divp© 1941 Nature Publishing Grouppdiv