Full Idea
Sense-data are usually conceived as necessarily private to individual observers, so the final crisis for the empiricist conception of perception was Wittgenstein's famous polemic against such private objects.
Clarification
A 'polemic' is a sustained verbal attack
Gist of Idea
As sense-data are necessarily private, they are attacked by Wittgenstein's objections
Source
report of Ludwig Wittgenstein (Philosophical Investigations [1952]) by Howard Robinson - Perception IV.1
Book Reference
Robinson,Howard: 'Perception' [Routledge 2001], p.91
A Reaction
Personally I remain unconvinced by Wittgenstein's very elusive argument, but I think there are plenty of other reasons for doubting whether the idea of sense-data throws much light on our understanding of the processes of perception.