Use of DEREF function

Hi everybody !

I would like to know if we can use the DEREF function to get one part of a REF column.

Example :
CREATE TYPE emp_type AS OBJECT
(eno NUMBER, ename VARCHAR2(20), salary NUMBER);

CREATE TABLE emp_table OF emp_type
(primary key (eno, ename));

CREATE TABLE dept_table
(dno NUMBER, mgr REF emp_type SCOPE IS emp_table);

INSERT INTO emp_table VALUES (10, 'jack', 50000);
INSERT INTO dept_table SELECT 10, REF(e) FROM emp_table e;

SELECT DEREF(mgr) from dept_table

DEREF(MGR)(ENO, ENAME, SALARY)
--------------------------------------------------------
EMP_TYPE(10, 'jack', 50000)


I would like to have only the name of the employee ...

Is that possible ?
Thanks a lot in advance, it's quit urgent !