THE REDUCING DIVISION 259 
and a paternal member fused together. Each of the 
visible chromatic bodies next divides into four parts, 
the set of four deeply staining bodies being known as a 
tetrad. Thus when there are four somatic chromosomes 
the number of tetrads appearing will be two (Fig. 32). 
A mitosis now ‘takes place, during which there is no 
further division of chromosomes, but half of each 
Fig.32 Fig.33 Fig.34 * 
Fig.37 
tetrad passes to either pole of the nuclear spindle, 
so that each daughter nucleus comes to contain two 
half-tetrads, each consisting of a pair of deeply-staining 
bodies (Fig. 34). This division is not followed by the 
production of a resting nucleus, for before any nuclear 
reticulum is formed, and while the half-tetrads still 
retain their definite appearance, the daughter nuclei 
divide again. At this second division in each nucleus 
17—2 
