514 Edmund B. Wilson. 



Figure i. 



Alydus pilosulus.— a, Contraction-phase of synaptic period, "accessory" (Jt) in the form of a con- 

 densed chromosome-nucleolus attached to a large plasmosome (p); h, spermatocyte-nucleus, middle 

 growth-period, showing large diffused chromosomes — "accessory" still attached to the plasmosome — 

 and the two condensed w-chromosomes on opposite sides of the nucleus; c, early prophase of first 

 division, showing all of the chromosomes, the larger ones condensing; d, late prophase, showing 

 ''accessory''' (Jt) and the two m-chromosomes still separate; e, slightly later prophase, showing all 

 of the chromosomes; /, initial anaphase, first division, the ra-chromosomes separating; ^, polar view of 

 metaphase-group, first division; h, polar view of metaphase-figure, second division; /, j, initial 

 anaphases, second division; k, spermatogonial metaphase-group; /, m, n, 0, anaphases of second 

 division. 



