[Illustration: FIG. 112.--Plan of the tomb of Ti.] [Illustration: FIGS. 113, 114.--Mastaba at Sakkarah, from Prisse.] In the tomb of Ptah-Hotep, of which we reproduce the principal side, the stele proper is on the left, but the figures and the funerary inscriptions cover all the central part of the richly decorated wall (Fig. 115). We see, then, that the stele is the one indispensable part of this complicated whole. It was, in fact, upon the formula with which it was inscribed, that the Egyptians depended for those magical agencies by which Osiris became the active medium of transmission between the living and the dead. "At the foot of the stele there was often a table for offerings, in granite, alabaster, or limestone. This was laid flat upon the ground (Fig. 92). [Illustration: FIG. 115.--Western wall in the chamber of the tomb of Ptah-Hotep, 5th dynasty. Drawn by Bourgoin.] "As a rule this was the only piece of furniture in the chamber; but occasionally we find, on each side of the stele and always placed upon the ground, either two small limestone obelisks, or two objects in that material resembling table legs hollowed out at the top for the reception of offerings." This chamber was left open to every comer. The entrance was in fact left without a door. To this rule Mariette found but two exceptions in the many hundreds of tombs which he examined.[167] [167] One of these exceptions is furnished by the tomb of Ti, of which we shall often have to speak (Fig. 114). The large public hall near the entrance to the tomb was separated from the two chambers farther in by a corridor closed at two points by doors, some remains of which were found in place when the tomb was opened. "Not far from the chamber, oftener on the south than the north, and oftener on the north than the west, a passage in the masonry, high, narrow, and built of very large stones, is found. The workmen employed upon the excavations christened it the _serdab_, or corridor, and their name has been generally adopted."[168] In Figs. 116-119 we give the plan and three sections of a mastaba at Gizeh which has four serdabs. [168] This is a word of Persian origin adopted by the Arabs. Its strict meaning is a dark subterranean opening, cave, or passage. "Sometimes the serdab has no communication with the other parts of the mastaba, it is entirely walled in, but in other instances there is a narrow quadrangular opening, a sort of pipe or conduit, which unites the serdab with the chamber. It is so small that the hand can only be introduced into it with difficulty.[169] [169] The tomb of Ti had two serdabs as well as three chambers; one of these was close to the door, the other in the innermost part of the mastaba. In the latter several statues of Ti were found, the best preserved being now in the museum at Boulak.