CRYPTOGAMS 301 
circumstances arise, they begin again their work of repro- 
duction and growth as actively as ever. 
339. Meaning of the name. — The suffix coccus is a Latin 
noun (plural cocc) meaning a grain or berry, and is a general 
term applied to any small, round organism consisting of a 
single cell; hence, micrococcus, a minute round body; proto- 
coccus, @ primitive form, or prototype of one-celled bodies ; 
and pleurococcus, which may be freely translated ‘‘ a one- 
sided little round body,” from the flattening of the adjacent 
sides during fission — plewro meaning lateral, or pertaining 
to the side. 
It is important to remember this definition, as the term 
coccus is of very frequent occurrence in works of biology, as a 
suffix for designating small round bodies of various kinds. 
340. Examination of a filamentous alga.— Place on a 
white dish a few drops of water containing some of the green 
pond scum common in stagnant pools and ditches. Exam- 
ine with a hand lens; of what does it appear to consist? 
Are the filaments all alike, or are they of different lengths 
and thickness? Soak a number of them in alcohol for half 
an hour and examine again; where has the green matter 
gone? Do these alge contain chlorophyll? (336; Exp. 65.) 
This class are called filamentous alge on account of their 
slender, threadlike thalli, which look like bits of fine floss 
floating about in the water. The bubbles of oxygen which 
they sometimes give off in great abundance cause the 
frothy appearance that has given rise to their popular 
name, “ frog spit.” 
341. Spirogyra. — The filamentous alge are very numer- 
ous, and a drop of pond scum will probably contain several 
kinds. At least one of these, it is likely, will be a Spi- 
rogyra, as this is one of the commonest and most widely 
distributed of them all. Place a filament under the micro- 
scope and notice the spiral bands in which the chlorophyll 
is disposed within the cells. It is from this spiral arrange- 
ment that the species takes its name. Do you notice any 
