A forged instrument, not being the contract of the party alleged to have made it, can, of course, confer no rights upon any person, with the single exception that the alleged maker may become liable to a bona fide holder through the application of the doctrine of estoppel.

The material alteration, whether made with fraudulent intent or not, of a negotiable instrument destroys the identity of the contract, and releases any party thereto who does not consent to such alteration.9

An immaterial alteration, i. e., one which does not change the tenor of the instrument, does not avoid it.