In Can I play an English horn part with a viola?, jjmusicnotes commented that "transposing down a fifth is a pretty straightforward practice" for violists. I'm not a string player, so I've never thought of this, but:
Can a violinist, violist, or cellist transpose by perfect fifth by just playing one string higher or lower? Can a bassist do this to transpose by perfect fourth? I don't see why they couldn't, but perhaps there are other problems that would arise.
Obviously there are issues of range, with a violin only going down to the G below middle C. But let's say a violinist sees the following music:
Can they just play this down a string to play it in the key of A?