TABLE OF CONTENTS 



Kill 



PAGE 



Juvenile and adult forms adapted to different relationships in 



heteroblastic development 143 



Juvenile form is primitive or is derived 145 



Primary leaves often arrested formations 145 



Reversion to the juvenile form 145 



Varying duration of juvenile form 145 



ILLUSTRATIVE EXAMPLES : 148-170 



1. Thallophyta ... 148-150 



Lemanea ... 148 



Batrachospermum 149 



Dumontia filiformis 149 



Polysiphonia Binderi 150 



Chara 150 



Sphacelarieae 150 



2. Bryophyta ............ 151 



3. Pteridophyta 151-153 



Equisetineae 151 



Lycopodineae 151 



Filicineae 151 



4. Gymnospermae I53-I55 



Cycadeae 153 



Pinus 153 



Larix 154 



Cupressineae 154 



Phyllocladus 155 



Sciadopitys . . 155 



5. Angiospermae 1 55-170 



A. Climbing plants 157-164 



1. Root-climbers 157 



2. Plants with tendrils 161 



B. Aquatic and marsh plants 164-165 



C. Xerophilous plants 165-170 



1. Acacias forming phyllodes 166 



2. Eucalyptus 167 



3. Dicotyledonous plants with cupressoid habit . . . 167 



4. Plants with arrested leaves ...... 167 



v 



SUMMARY 17 



REVERSION TO THE JUVENILE FORM 171-174 



Reversions experimentally produced by changes of conditions . . 171 



Reversion associated with definite developmental stages . . . 171 



Reversion in Bryophyta . . . 171 



Reversion in Spermaphyta I7 2 



CONCLUSION OF THE DEVELOPMENT . 174 



