CONTENTS 



INTRODUCTION ^ 



On the exine morphology of the saccate pollen grains in recent 



gymnosperms ^ 



ILLUSTRATIONS ^ 



Gymnospermae (Abies — Widdringtonia) 5 



Pteridophyta (Acrostichum — Xiphopteris) 45 



Bryophyta (Acroschisma — Voitia) "" 



SUPPLEMENT 125 



On new methods in physical cell research and their application 



in studies of pollen grains and spores. By B. M. Afzelius . . 125 



On the cutting of ultra-thin sections. By J. Radwan Praglowski 135 



INDEX 148 



MARINE 

 BIOLOGICAL 

 LABORATORY 



LIBRARY 



WOODS HOLE, MASS. 

 W. H. 0. !. 



J 



G6 ' 



1 



