Section 26. In sections twenty-seven to thirty-nine, inclusive, the word “absentee” shall mean a beneficiary who has disappeared, absconded or is absent from the commonwealth, or has disappeared or absconded from the place without the commonwealth, where he was last known to be, and it is not known by the petitioner where he is, and the date of such disappearance or absconding and of the time when it was last known by the petitioner where he was and when he was last heard from or heard of shall have been more than fourteen years before the filing of the petitions provided for in said sections twenty-seven to thirty-nine, inclusive.