No will shall be valid unless it be in writing and signed by the testator, or by some other person in his presence and by his direction, in such manner as to make it manifest that the name is intended as a signature; and moreover, unless it be wholly in the handwriting of the testator, the signature shall be made or the will acknowledged by him in the presence of at least two competent witnesses, present at the same time; and such witnesses shall subscribe the will in the presence of the testator, and of each other, but no form of attestation shall be necessary.