As per Sec 176 any member of a company entitled to attend and vote at a meeting of the company shall be entitled to appoint another person (whether a member or not) as his proxy to attend and vote instead of himself; but a proxy so appointed shall not have any right to speak at the meeting: Provided that, unless the articles otherwise provide-
1. this sub- section shall not apply in the case of a company not having a share capital;
2. a member of a private company shall not be entitled to appoint more than one proxy to attend on the same occasion; and
3. a proxy shall not be entitled to vote except on a poll.
Conclusion: Yes! Mr.X can be appointed as proxy of CD