82 BIOLOGY 



Many biologists, for example Haeckel, Brooks, and 

 Galton, had hinted at this theory, but it remained for 

 Weismann to give it its definite expression. 



What is meant by this organic continuity ? Suppose 

 we have a fertilised egg-cell which is endowed with certain 

 qualities. This cell divides into two, each of which has 

 all the characters of the original ; this division goes on 

 repeatedly, and we may suppose that all the resultant 

 cells are endowed with the original characteristics. But 

 now a division of labour and other changes occur among 

 the resultant cells, so that the majority of the cells go 

 to form the body. These naturally must lose their 

 general characteristics as some are specialised for one 

 purpose, some for another ; but in the meantime there 

 are certain cells set aside and kept apart from the 

 specialisation, and they retain their general or em- 

 bryonic characteristics. They form the future repro- 

 ductive cells. 



A cell derived from these will be in the same position 

 as the cell we started with, so it will develop into the 

 same kind of organism, and this will be repeated just 

 so long as reproduction lasts in the race. 



So far so good ; but we may ask, In how many forms 

 has this early setting aside of the future reproductive 

 or germ-cells been observed ? It has undoubtedly been 

 observed in certain worms, in some crustaceans, and in 

 some insects, and also in a number of organisms both 

 plant and animal. It is at a late period, however, in 

 the development of the higher organisms that these 

 cells are set aside, and this was raised as an objection 

 to the theory, but Weismann supplied a more general 



