"Interesting! It's the very heart and core of the trade." Dr. Surtaine
leaned forward, to tap with an earnest finger on his son's knee, a
picture of expository enthusiasm. "Here's the theory. You see, along
about March or April people begin to get slack-nerved and out-of-sortsy.
They don't know what ails 'em, but they think there's something. Well,
one look at that ad. sets 'em wondering if it isn't their kidneys. After
wonder comes worry. He's the best little worrier in the trade, Old
Lame-Boy is. He just pesters folks into taking proper care of
themselves. They get Certina, and we get their dollars. And they get
their money's worth, too," he added as an afterthought for Hal's
benefit, "for it's a mighty good thing to have your kidneys tonicked up
at this time of year."

"But, Dad," queried Hal, with an effort of puzzled reminiscence, "in the
old days Certina wasn't a kidney remedy, was it?"

"Not specially. It's always been _good_ for the kidneys. Good for
everything, for that matter. Besides, the formula's been changed."

"Changed? But the formula's the vital thing, isn't it?"

"Yes, yes. Of course. Certainly it's the vital thing: certainly. But,
you see,--well,--new discoveries in medicine and that sort of thing."

"You've put new drugs in?"

"Yes: I've done that. Buchu, for instance. That's supposed to be good
for the kidneys. Dropped some things out, too. Morphine got sort of a
bad name. The muckrakers did that with their magazine articles."