212 THE PERPETUATION OF ADAPTATIONS 



extraordinary hypothetical division during maturation, the 

 reduction division. 



The fulfilment of this prophecy by a host of different observ- 

 ers was a remarkable justification of the imagination in science. 





H 



FIG. 89. Middle and end phases of mitosis. G, Metaphase showing the 

 longitudinal split of the chromosomes; /7, the end phase or anaphase with the 

 daughter chromosomes separating, between them the inter-zonal fibers (^/); 

 the centrosomes are divided in preparation for the next following mitosis; / and 

 /, final stages in daughter nuclei formation and division of the cell; n, the dis- 

 carded nucleolus; ep, equatorial plate. (From Wilson.) 



The reduction division, in some form or other, often complicated 

 and atypical, was revealed in type after type of animals and 

 plants, until today it is generally, if not quite universally, ac- 

 cepted as a typical phenomenon of maturation. 



