I am trying to find out the names and authors of two stories I read in the '60s. Plot 1-A machine called chronos changes history but the people don't realize it (as they are bring changed from human beings to slithery globs of jelly). The punch line is, "Nothing has changed!" Plot 2-An astronaut makes contact with an alien and he invites him to earth. But nobody can see him when he lands because he is microscopic. I've been trying to find these two stories to reread them for decades. Thanks!