Xll CONTENTS. 



III. SURVEY OF THE REPRODUCTIVE PROCESS IN THE 

 ANIMAL KINGDOM. 



Page. 



1. General Character of the Process, . . 68 



2. Reproduction in the Protozoa, ... 74 



3. In the Coelenterata, .... 81 



4. In the Echinodermata, .... 84 



5- In the Polyzoa, ..... 87 



C. In the Tunicata, ..... 89 



7. In the higher Mollusca, .... 91 



8. In the Helmintha, .... 94 



9. In the Annelida, .... 99 



10. In the higher Articulata, . . . 102 



11. In the Vertebrata, .... 106 



12. Concluding Remarks, .... 107 



IV. NATURE AND VARIETIES OF ALTERNATION OF GENE- 

 RATIONS. 



1. Points of Agreement and Diversity in cases of Al- 

 ternation, ..... 109 



2. Protomorphic Alternation, as in the Trematoda, 

 from Gemmation in the Early Stage of Develop- 

 ment, ...... 112 



3. Gramomorphic Alternation, as in the Polypifera, 



from a later Gemmation, in the evolution of Sex, 117 



4. Relations of these two forms of Alternation, . 128 



5. Their Co-existence in the case of the Cestoid Worms, 131 



6. Orthomorphic Alternation, as in the Aphides, from 

 Gemmation in the evolution of the Typical Or- 

 ganization, . . . . .133 



7. Reference of the best known cases of Alternation, 



to one or other of the foregoing heads, . 136 



8. Co-existence of all the three forms in the case of 



some Annelida, ..... 137 



9. Alternation in the Salpce, .... 140 

 10. Protomorphic and Gamomorphic Alternation in 



Mosses and Ferns among Plants, . . 142 



V. PULLULATION. 



1. Notice of a Series of Successive Gemmations, inter- 

 polated at certain points, . . . 146 



