“small animal” through the air. at first, the “bad-small-thing” and the “changed-bad-small-thing” did not move through the air from one “small animal” to the next.
then they passed the “bad-small-thing” from one “small animal” to the next, to change it more. they did this ten times with both the “bad-small-thing” and the “changed-bad-small-thing”. they found that the “changed-bad-small-thing” grew easier and more often after passing from “small animal” to “small animal”.
next, they wanted to see if the “passed-changed-bad-small-thing” could pass from “small animal” to another “small animal” through the air. the doctors put the “small animals” in boxes that did not let the “small animals” touch, but air could pass between 