146 LUTHER BUKBANK 



This structure lies at the heart of every germ 

 cell through which a living organism propagates 

 its kind. 



The pollen grain of the plant, for example, is 

 the carrier of such a germinal nucleus. The pol- 

 len grain itself is a structure of almost micro- 

 scopic size, yet it is colossal in comparison with 

 the infinitesimal fleck of germinal matter that 

 lies at its center. Yet the modern microscope 

 can so magnify this fleck of matter that some- 

 thing of the mechanism of its vital parts 

 becomes visible. 



The microscopist tells us that within the ger- 

 minal nucleus there are to be seen sundry films 

 of matter, arranged to form a sort of skeleton, 

 which are readily stained under his manipula- 

 tion and which he therefore names "chromo- 

 somes" colored bodies. He observes that the 

 nuclei in cells of different plants and animals 

 have these infinitesimal chromosomes arranged 

 in different characteristic groups, differing in 

 number in different species, but always the same 

 for each and every cell of plants or animals of 

 a given species. 



The enlarged vision of the microscopist en- 

 ables him to assure us that when two germ cells 

 of the opposite order come together when, for 

 example, the nucleus of a pollen grain blends 



