ALGZ 59 
THE ConJUuGATAa 
The members of the second subsidiary order of the 
green alge, the Conjugate, are mostly fresh-water 
plants, having very marked characteristics, and distin- 
Fic. 13 (Conjugate).— A, two filaments of Spirogyra showing the be- 
ginning of conjugation; each cell contains a single large spiral chlo- 
roplast with the pyrenoids, »; B and C, later stages of conjugation; in 
C the contents of one of the conjugating cells has passed completely 
over into the other, the united protoplasmic masses forming the resting- 
spore, sp; D, Closterium, one of the Desmids or unicellular Conjugate ; 
Pp, ® pyrenoid; E, two views of another Desmid, Staurastrum; the 
shaded portion represents the chloroplast; F, a Desmid, Cosmarium, 
in process of cell-division. 
guished from most of the other alge by the complete 
absence of ciliated cells. The most familiar members of 
the group are the “ pond-scums,” which occur in large, 
frothy masses, floating in quiet water. The lowest of 
the order are the Desmids, perhaps the most beautiful 
of all unicellular plants (Fig. 18). 
The lowest of the desmids are simple oval cells, with 
