APPENDIX II 



THE MATERIAL BASIS OF INHERITANCE 



In Appendix I, it has been mentioned that 

 Weismann regarded the chromosomes of the nucleus 

 as the bearers of hereditary characters, and more 

 recent work has added to the probability of this 

 view, while not as yet providing anything winch can 

 be called proof. That some, if not all, the hereditary 

 characters are determined by the nucleus of the 

 germ-cell is indicated by several facts. In the first 

 place, the spermatozoon consists of little else but a 

 nucleus with a vibrating tail, and the tail may be 

 shed as the spermatozoon enters the ovum. Secondly, 

 experiments in fertilising non-nucleated fragments 

 of sea-urchin eggs by sperm of a different species, 

 give evidence that the hereditary characters of the 

 resulting larvae are exclusively those of the paternal 

 species. This conclusion however has been disputed, 

 and can only be regarded as probable rather than 

 certain. Again, experiments in fertilising one egg 

 simultaneously by more than one spermatozoon, lead 



