XII.] CONJUGATION AND SEXUAL REPRODUCTION 145 



the plane ot division {x — x) the halves of the wreaths may be 

 built up of different combinations of ids. 



Hence, according to this hypothesis, in the first ' reducing 

 division,' we find in the equatorial plate of the nuclear spindle, 

 twenty-four double idants, the halves of which lie over each 

 other in two rows (Fig. IV. 5), and, which separating into single 

 idants, bring about the second ' reducing division ' (Fig. IV. 6). 



5. 



1. 



Fig. VI. 

 Formation of double idants in Pyrrhocons. 



Fig. VII. 



A wreath, formed of the four idants A, A, B, B, about to divide, 

 through the moveable plane x — .r, into tw^o double idants. The small 

 letters denote the ids, of which only four are shown in each idant. 



For some years I have imagined to myself the grouping of 

 the ids into idants, by the arrangement of the former in the 

 figure of a wreath, a form which renders possible a moveable 

 plane of division. It would seem that this arrangement actually 

 obtains in the ' reducing division,' and that nature produces a 

 form which I had only conceived as a diagram. 



The formation of wreaths by the idioplasm, during the 



VOL. II. L 



