12 



OUTLINES OF PLANT LIFE. 



observe the form and color of single plants, many consisting of two or 

 more cells still joined together, resulting from cell division. (1[i7, fig. lo.) 



m B 



Fig. -io.—Phurococcus viridis. A, a single individual; 5, a colony shortly after 

 division ; C, the same after separation. Magnified 540 diam.— After Strasburger. 



Fig. II. — Various diatoms, a, Synedra : 6, Pleurosigma ; c, d, Gr-amtnatflphora^ 

 side and top views ; e, colony of Gom^hotiemn, with branched stalks attached to an 

 alga ; y, g, single cells of same, more magnified, top and side views ; A, colony of 

 Diatoma, the cells connected into a zigzag band ; ?', k, colony and individuals {top and 

 side views) of Frngillaria : I, m, n, Cocconema. In in the pair is surrounded hy 

 jelly preliminary to the escape of the protoplasm and the formation of two new cells 

 (auxospores) which has been completed in «.— After Kerner. 



18. Shelled plants. — ^Other one-celled plants constitute a 

 group known as diatoms, found in both fresh and salt waters, 

 either attached or free-swimming (figs, ii, 12). The dia- 



