THE METHOD OF EUGENICS 11 



most striking fact is the exact division of the chromatin 

 (Fig, 2). We know enough to say that the nucleus is the 

 center of the cell's activity and for reasons that we shall 

 see immediately it is probable that the chromatin is the 

 most active portion of the nucleus. 



Attraction-sphere enclosing 

 two centrosomes 



Nu , 

 clcus 1 



Plaemo- 

 flome or 

 true nucle- 

 olus 

 Chromatin- 

 network 

 Linin-net- 

 work 



Karyoaome, 

 net-knot, or 

 chromatin- 

 nucleolus 



Plastids lying in 

 the cytoplasm 



—^ Vacuole 



Passive bodies 

 (metaplasm or 

 paraplasm) sus- 

 pended in the 

 cytoplasmic 

 nieshwork 



Fig. 1. — Diagram of a cell. Its basis consists of a meshwork containing 

 numerous minute granules (microsomes) and traversing a transparent ground 

 substance. From E. B. Wilson: "The Cell in Development and Inheritance." 



The fertilization of the egg (Fig. 3) brings together de- 

 terminers from two germ plasms and we loiow that, on the 

 whole, the two germ cells play an equal role in carrying 

 determiners. Now the germ cells are of very different 

 size in the female (egg) and the male (sperm). Even the 

 nuclei are different; but the amount of chromatic substance 

 is the same. Hence it seems probable that the chromatic 

 substance is the carrier of the equal determiners. 



But if determiners from the male are added to those 

 from the female in fertihzation it would seem necessary 



