Manis owns 100 shares of stock of the Linquist Corporation. She sells her stock to Sosnik and delivers to him: (1) her stock certificate for 100 shares and (2) a written, signed assignment of the 100 shares to Sosnik. The assignment form printed on the back of the share certificate is left blank and is not signed. Sosnik refuses to take the certificate and the assignment on the ground that Manis must fill in and sign the assignment form on the stock certificate to make the transfer of stock effective. Is he correct? Discuss.