In case bureaus for vocational training and placement, or other similar bureaus, are established by local school authorities, the director shall co-operate with such bureaus in dealing with the employment of children between the ages of fourteen and eighteen years, in such manner as may be advisable. The director shall use all reasonable means to promote the establishment of bureaus for vocational training and placement, in connection with vocational education by public school authorities throughout the State. Until bureaus for vocational training and placement, or other similar bureaus, have been established by local public school authorities, for the purposes of directing, advising, and assisting children in the selection of suitable vocations, the director shall provide school principals and all public employment offices with special blank forms for the registration of all children having employment certificates, as required by law, and leaving school lawfully in search of employment. Each child applying for employment may register at a public or other approved school with the principal of such school; and the principals of public or other approved schools are hereby authorized and required to register such applications for employment, to assist and advise each applicant in the selection of a vocation, in such manner as may be necessary, and to transmit immediately to the superintendent of the district branch office all applications for employment registered. The superintendent of each public employment office shall co-operate with the school principals in his district in endeavoring to secure suitable positions for children leaving school lawfully to enter a vocation, and shall guide and induce minors to enter promising vocations; and each principal shall acquaint the teachers and pupils of his school with the purpose and functions of the public employment office in placing juveniles.