Listen to part of a talk in a botany class.OK. So we've talked about some different types of root systems of plants, and I've shown you some pretty cool slides,but now I want to talk about the extent of the root system―the overall size of the root system...the depth.I want to tell you about one particular experiment. I think you're going to find this pretty amazing.OK. So there was this scientist...this very meticulous scientist decided that the best place to see a whole root system―to actually see how big the entire system got―the best place would be to grow it...where?Um, water?In water. So he took rye plants―it was rye plants―and he started growing them in water.Now, you've all heard of growing stuff in water before, right?It's done commercially, right? Uh, like to grow vegetables and flowers?Right. They grow all kinds of commercial crops in water.So, if you're growing things in water, you can add the fertilizer.What do you need to do to that water besides put fertilizer in it? Anyone ever actually tried to grow plants in water?You must bubble water through it. Bubble gas through it. I'm sorry, you must bubble gas through it.So, gas, you have to bubble through. Think about the soil we talked about last week, about growing plants in soil.Think about some of you who have killed your favorite houseplants, 'cause you loved them too much.If you overwater, why do your favorite houseplants die?Oh, no oxygen.Not enough oxygen for the roots...which do what twenty-four hours a day in all seasons?