CONTENTS. Xlll 



Page. 



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



3. — Ramified disposition of Plants and Zoophytes from 



Adhesion of the Genimse, . . . 149 



4, — Such adhesion a point of minor importance in the 



present enquiry, .... 160 



5. — Pullulation itseK of secondary importance to Alter- 

 nation, ...... 153 



VI. — Embryogeny, as representing one Form of 



Alternation. 



1. — Representative Phenomena in the Higher Species, 156 



2. — Representation in Embryonic Develoj^ment, . 167 



3. — Illustration from Dujjlex 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 aud Zooids, 174 

 9. — Illustration from the reproduction of Phanero- 

 gamic and Crjrptogamic Plants, . . . 180 

 10. — Correspondence inferred between the process of 



Maturation and Gamomorphic Alternation, . 188 



VIII, — Relations of Ova and Gemm^. 



1. — Points of distinction between Ova and Gemmae, 



with notice of transitional forms, . . 190 



