CONTENTS. Xlll 



Page. 



2. Most frequent in the Middle Stage of Development, 147 



3. Ramified disposition of Plants and Zoophytes from 



Adhesion of the Geininse, . . . 149 



4. Such adhesion a point of minor importance in the 



present enquiry, .... 150 



5. Pullulation itself of secondary importance to Alter- 

 nation, . . . . . 153 



VI. EMBRYOGENY, AS REPRESENTING ONE FORM OP 

 ALTERNATION. 



1. Representative Phenomena in the Higher Species, 156 



2. Representation in Embryonic Development, . 157 



3. Illustration from Duplex Monstrosity, . . 157 



4. From the Development of the Polyzoa, . . 160 



5. From that of Cestoid Worms, . . . 161 



6. From that of the Echinodermata, . . 162 



7. Essential Community of Nature, . . 164 



VII. REPRESENTATION OF THE OTHER FORMS. 



1. Representation of Orthomorphic Gemmation in the 



Higher Species, .... 166 



2. Representation of Gamomorphic Alternation in the 



Maturation of Sex, .... 167 

 3. Illustration from the Periodic and Late Develop- 

 ment of the Organs, .... 167 

 4. From the case of the Polyzoa, . . . 170 

 5. From some aberrant Crustacea, . . . 172 

 6. From the later phases of the Cestoid Entozoa, . 173 

 7. From the reproduction of the Polypifera, . 173 

 8. Points of distinction between Organs and Zooids, 174 

 9. Illustration from the reproduction of Phanero- 

 gamic and Cryptoganiic Plants, . . . 180 

 10.- Correspondence inferred between the process of 



Maturation and Gamomorphic Alternation, . 188 



VIII. RELATIONS OF OVA AND GEMMJE. 



1. Points of distinction between Ova and Gemmae, 



with notice of transitional forms, . 190 



