CONTINUITY OF THE GERM-PLASM, 



ETC. 



CONTENTS. 



PAGE 



Introduction ........... 167 



I. The Germ-plasm . ......... 176 



1. Historical development of the theory as to the localization 



of the germ-plasm in the nucleus . . . . .176 



2. Nageli's ' idioplasm ' is not identical with Weismann's 



' germ-plasm ' 183 



3. A retransformation of somatic idioplasm into germ-idio- 



plasm does not take place ...... 186 



4. Confirmation of the theory as to the significance of the 



nuclear substance afforded by Nussbaum's and Gruber's 

 experiments on regeneration in Infusoria . . . 188 



5. The nucleoplasm changes during ontogeny according to a 



certain law ......... 188 



6. The identity of the daughter-nuclei produced by indirect 



nuclear division, as assumed by Strasburger, is not 

 necessary for my theory ...... 190 



7. The gradual decrease in complexity of the structure of the 



nucleus during ontogeny ...... 193 



8. Nageli's view on the germs (' Anlagen ') in the idioplasm. 195 



9. The manner in which germ-cells arise from somatic cells . 198 



10. * Embryonic ' cells in the mature organism . . . 199 



11. The rule of probability is against a retransformation of 



somatic idioplasm into germ-plasm .... 201 



12. The regular cyclical development of the idioplasm founded 



upon phylogeny by Nageli ...... 203 



13. It follows from phyletic considerations that the germ-cells 



have not arisen at the end of ontogeny .... 204 



14. They originally arose at the beginning of ontogeny, but at 



a later period the time of their origin was displaced . 205 



15. A continuity of the germ-celis does not now exist in most 



cases .......... 208 



16. But there is a continuity of the germ-/>/a5;« . . . 208 



17. Strasburger's objection to my supposition that the germ- 



plasm passes along distinct routes .... 213 



18. The cell-body may remain unchanged when the nucleus is 



changed .......... 214 



19. It is conceivable that all somatic nuclei may contain some 



germ-plasm 215 



