224 ESSENTIALS OF BOTANY 
286. Minute Structure. — Make a drawing of one or more filaments 
as seen with Lp. Draw the basal and the apical cell as seen with h.p. 
Under h.p. draw one of the cells near the middle of a filament 
and note: 
(a) The large chromatophore, which almost. fills the cell. 
(6) The nucleus (if it can be seen). 
(c) Pyrenoids. Test with iodine to see whether starch is present. 
287. Reproduction. 
I. Asexuvan 
With h.p. look for cells in any of the filaments in which the proto- 
plasmic body of the cell has changed into a pear-shaped cell (zodspore) 
furnished at the smaller end with a fringe of cilia, or bristle-shaped 
appendages. Look also for the pear-shaped zodspores swimming 
freely about by means of their cilia. Study their movements, then 
run in iodine under one edge of the cover-glass, to kill the cells, and 
note the form and structure of the zodspore. Draw. If any germi- 
nating zodspores can be found, draw them. 
II. Sexvau 
With h.p. look for filaments which have large swollen cells at 
intervals along their length. Such a cell is called an odgonium and 
contains one female gamete, or egg. Note: 
(a) The general form of the oégonium. Draw. 
(b) The pore or opening to allow of fertilization. 
(c) The egg-cell which nearly fills the oégonium. 
Look for antheridia, groups of rather flat, tabular cells occurring 
near odgonia. These produce ciliated sperms, which enter the egg- 
cells and fertilize them. Draw a group of the disk-shaped cells. 
Look for fertilized ege-cells, which may be distinguished by their 
heavy cell-walls. This fertilized cell is an odspore. In the odspores 
seen note : 
(a) The dense cell-contents, due to the accumulation of food 
material. Test with iodine solution for starch. 
(>) In the older odspores the division of the contents into ciliated 
zoéspores, each of which may grow into a new filament of Gidogonium. 
Draw odspores at various stages. 
