522 Wisconsin Academy of Sciences, Arts, and Letters. 



EXPLAXATIOX OF PLATE XXX. 



Figs. 24-25, Successive stages of cleavage, x 1500. 



Figs. 26-28, Successive stages of cleavage as found in differ- 

 ent parts of the same cell, x 1500. 



Fig. 29, Late stage of cleavage. Xuclei arranged in pairs 

 with cleavage planes cutting in between the adja- 

 cent nuclei, x 1500. 



Fig. 30, Beginning of the separation of the uninucleate seg- 

 ments, x 1500. 



Fig. 31, Cross section of cell in early stage of cleavage with 

 the cleavage furrows formed by botli plasma and 

 vacuolar membranes, x 600. 



Fig. 32, Portion of vertical section of two adjacent cells, one 

 of which is undergoing cleavage, x 1500. 



Fig. 33, Portion of vertical longitudinal section of cell in late 

 cleavage stage, x 1500. 



Figs. 34-35, Uninucleate segments containing large irregular 

 nuclei, x 1500. 



Fig. 36, Young swarm spores with cilia, x 1500. 



Fig. 37, Mature swarm spores, x 1500. 



Fig. 38, Anterior end of mature swarm spore, showing loco- 

 motor apparatus, x about 3000. 



Fig. 39, Giant swarm spores. Mostly binucleate, x 1500. 



Fig. 40, Longitudinal sections of cells of very young net, x 

 1500. 



Fig. 41, Longitudinal sections of somewhat older cells. Each 

 cell still contains a single nucleus and a single pyre- 

 noid, X 1500. 



Fig. 42, Cross sections of cells in same net as those in Fig. 

 41, X 1500. 



Fig. 43, Binucleate stage of young cell, x 1500. 



Fig. 44, Section of a quite large cell containing but two large 

 nucl*^i, x 1500. 



