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-cells does not now exist in most 



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



16. But there is a continuity of the germ-/)/r75;;/ . . . 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 



