How to make a line of objects appear one by one

I’m trying to make an animation where a line of objects appear one at a time.
I’ve created the line using dupliframes, but I can’t work out how to make them appear one after another.

Ideally I’d like to be able to animate one instance of the object (to have it fade on or do something else) and have all the other objects do the same thing offset by ever increasing intervals. Is that possible?

thanks.