XIV 



CONTEXTS. 



2. — Nature of the Germs in the Viviparous Aphides and 

 allied Insects, ..... 



3. — Nature of the Ei:)hii3pial and Common Eggs in En- 

 tomostraca and Rotifera, 



4. — Development of Unimpregnated Ova in certain In- 



5. — Occasional development of Unimpregnated Ovules 



in Plants, ..... 



G. — Nature of the Viviparous Flowers of Plants, 

 7. — Indications of a tendency to development in the 



Sexual Elements singly, 

 8. — Essential community of nature between Ova and 



Gemmae, ...... 



0. — Question of the necessary recurrence of Sexual 



Generation, ..... 



10. — Bearing on the theory of Alternation of Generations, 



IX. — Summary of Conclu signs. 



1. — Recapitulation of Results, - 



2. — Formula of the Genetic Cycle, 



3. — Modification for the higher Animals, 

 4. — Extension for Pullulation, 



5. — Concluding Remarks, 



Page, 

 101 



193 



195 



199 



2( 



200 



202 

 204 



206 



208 



212 

 216 

 216 

 218 

 219 



X. — CAisES Simulating Alternation of Generations. 



1. — Casual Alternation of Gemmation and Generation, 221 



2. — Alternation of Diverse Gemmations, , . 221 



3. — Atavism, ..... 222 



4. — Metamorphosis, ..... 223 



5. — Sperm atop hores and Sporophores, . . . 225 



XI. — Homological Relations of the Structures concerned 



IN the Genetic Cycle. 



1. — Nature of the ultimate Sexual Elements, . 229 

 2, — Homological Relations of the Germinal and Sjjer- 



matic Elements, .... 234 

 3, — Links of the Genetic Cycle in the several Groups of 



Organized Beings, ^ - . . 237 



