THE GREAT GROUPS OF ALG^E 29 



springs. The filaments are simple, and are not anchored by 

 a special basal cell, as in Ulothrix and Edogonium. The 



FIG. 13. Spirogyra, a Conjugate form, showing one complete cell and portions of 

 two others. The band-like chloroplasts extend in a spiral from one end of the 

 cell to the other, in them are imbedded nodule-like bodies ( pyrenoids), and near 

 the center of the cell the nucleus is swung by radiating strands of cytoplasm. 

 CALDWELL. 



cells contain remarkable chloroplasts, which are bands pass- 

 ing spirally about within the cell wall. These bands may 



FIG. 14. Spirogyra, showing conjugation : A, conjugating tubes approaching each 

 other; B, tubes in contact but end walls not absorbed: C, tube complete and con- 

 tents of one cell passing through; D, a completed zygospore. CALDWELL. 



