THE GREAT GROUPS OF ALGJE 
245 
springs. The filaments are simple, and are not anchored by 
a special basal cell, as in Ulothrix and Edogonium. The 
FIR. 212. 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. 
CALDWBLL. 
cells contain remarkable chloroplasts, which are bands pass- 
ing spirally about within the cell wall. These bands may 
FIG. 213. 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. 
