1. Every stockholder entitled to vote at a meeting of stockholders or to express consent or dissent without a meeting may authorize another person or persons to act for him by proxy.2. Every proxy must be signed by the stockholder or his attorney-in-fact. No proxy shall be valid after the expiration of eleven months from the date thereof unless otherwise provided in the proxy. Every proxy shall be revocable at the pleasure of the stockholder executing it, except as otherwise provided in this section.3. The authority of the holder of a proxy to act shall not be revoked by the incompetence or death of the stockholder who executed the proxy unless, before the authority is exercised, written notice of an adjudication of such incompetence or of such death is received by the corporate officer responsible for maintaining the list of stockholders.4. Except when other provision shall have been made by written agreement between the parties, the record holder of shares which are held by a pledgee as security or which belong to another, upon demand therefor and payment of necessary expenses thereof, shall issue to the pledgor or to such owner of such shares a proxy to vote or take other action thereon.5. A stockholder shall not sell his vote or issue a proxy to vote to any person for any sum of money or anything of value, except as authorized in this section and section six thousand twenty.6. A proxy which is entitled "irrevocable proxy" and which states that it is irrevocable, is irrevocable when it is held by any of the following or a nominee of any of the following: (b) A person who has purchased or agreed to purchase the shares.7. Notwithstanding a provision in a proxy, stating that it is irrevocable, the proxy becomes revocable after the pledge is redeemed. This paragraph does not affect the duration of a proxy under subdivision two.8. A proxy may be revoked, notwithstanding a provision making it irrevocable, by a purchaser of shares without knowledge of the existence of the provision unless the existence of the proxy and its irrevocability is noted conspicuously on the face or back of the certificate representing such shares.9. No director, officer, clerk, teller or bookkeeper of a corporation shall act as proxy at any meeting of such corporation.