You will observe:Several typesofvery simple greenplantscalled algae.
Manywill be stained blue-black within their cells. Some will have only one
cell andotherswill seem to live ingroupsor colonies orstrands.
Algae are the simplest water plants which contain chlorophyll, that
chemical which is necessary in the productionoffood for all forms oflife.
Some algae live only in fresh water and others only in salt water. These plants
(like all green plants) can manufacturefood in the form ofa simple sugar.
Butplantscannotstore sugar in their cells. Withina cell, the sugar is miracu-
lously changed by a chemical process into starch. Starch can bestoredfor
future use. Diluteiodine stains the starch to a blue-black color.
Scientists have been seeking a way to strain large quantities of these
importantgreen plantsoutofthe water. It'spossiblethatalgae may someday
be animportantsource of food forhumanbeings.
GROWING YEAST PLANTS
Materials:A cake of yeast or a packageofdried yeast powder, five tea-
spoons ofmolasses, ahalf-pintjellyjarwith a cover,tapwater, a medicine
dropper,a toothpick.
Follow this procedure:Fill thejartwo-thirdsfull of tap water. Dissolve
fiveteaspoonsofmolasses in the water. Ifyou use cake yeast, crumble one-
fourthofthe cake in the molasses and water solution. Ifyou use yeastpowder,
pouraboutone-fourthofthecontentsof the package into the solution. Put
the lid on thejar. Set it in a warm place forabout48 hours.
Then, with the medicinedropper,put adropofthe yeast-molasses mixture
in the middle of a clean slide. Using thetoothpick,spreadthedropofwater
on the slide sothatit covers a space in the middleaboutthe sizeofa small
coin. Carefully cover this with a cover slip and observeunderthe microscope.