“Well, if any new fruit or vegetable should turn up now, a chemist would analyze it to find out just what it was composed of. Then the doctors who make a study of such things would ‘try it on a dog,’ or more likely on a rabbit or guinea pig, to find out if it had any value as a medicine. They try every new substance in that way in fact, whether it is an original substance just discovered or some new compound. They even tried nitro-glycerine, and found it to be a very valuable medicine. So, too, they have got some of our most valuable drugs from coal oil, simply by trying them.” “Good for modern science!” said Phil. “But, Ed, what were the other new things the colonists found in this country?” “There were many. But those that have proved of most importance are corn, tobacco, tomatoes, watermelons, turkeys, Irish potatoes, and sweet potatoes.” “Oh, come now,” said Irv, raising his head and resting it on his hand, “you said _Irish_ potatoes.” “And why not? They are a very important product, and the crop of them sells for many millions of--” “_But_ they didn’t originate in this country, did they? Weren’t they brought here from Ireland?” “Not at all. They were taken from here to Ireland.” “Then why are they called Irish potatoes?” “Because they proved to be so much the most profitable crop the Irish people could raise that they soon came to be the chief crop grown there. I don’t know whether the colonists found any of them growing wild in Virginia or not. They are supposed to have originated in South America and Mexico. At any rate, they are strictly native Americans. By the way,” said Ed, “the people who thought tomatoes poisonous were not so very far out in their reckoning. Both the tomato and the potato are plants belonging to the deadly nightshade family, and the vines of both contain a virulent poison.” “Perhaps somebody tried tomato vines for greens,” said Phil, “and got himself ready for the coroner before the tomatoes had time to grow and ripen.” “That isn’t unlikely,” said Ed. “At any rate, an experiment of that kind would have gone far to give the fruit a bad name.” “However that may be,” said Irv, “it is pretty certain that men must have found out what was and what wasn’t good to eat mainly by trying. There’s salt now. It is the only mineral substance that men everywhere eat. All the rest of our foods are either animal or vegetable.” “And that’s a puzzle,” replied Ed. “Man must have got a very early taste of salt, or else there wouldn’t be any man.” “How’s that?” “Why, the human animal simply can’t live without salt. He digests his food by means of an acid which he gets from salt, and from nothing else whatever. So he must have had salt from the beginning.” “The Garden of Eden must have been a seaport then,” mused Phil. “Adam and Eve probably boiled their new potatoes in water dipped up from the docks.” The boys laughed, and Ed continued:--