THE GKEAT GRODPS OF ALG^ 



29 



springs. The filaments are simple, and are not anchored 

 by a special basal cell, as in Ulothrix and (Eclogoiiium. The 



Fig. 13. Spirogyi^a, a Conjugate form, showing one complete cell and portions of 

 iwo 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 



Fia. 14. Spirogyra. showing conjugation : A, conjugating tubes api)roaching 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. 



