Tarzan would so choose.

Again came the soft sound of padded footsteps in the reeds--closer
this time. Werper abandoned his design. Before him stretched the
wide plain and escape. The jewels were in his possession. To
remain longer was to risk death at the hands of Tarzan, or the
jaws of the hunter creeping ever nearer. Turning, he slunk away
through the night, toward the distant forest.

Tarzan slept on. Where were those uncanny, guardian powers that had
formerly rendered him immune from the dangers of surprise? Could
this dull sleeper be the alert, sensitive Tarzan of old?

Perhaps the blow upon his head had numbed his senses, temporarily--who
may say? Closer crept the stealthy creature through the reeds.
The rustling curtain of vegetation parted a few paces from where
the sleeper lay, and the massive head of a lion appeared. The beast
surveyed the ape-man intently for a moment, then he crouched, his
hind feet drawn well beneath him, his tail lashing from side to
side.

It was the beating of the beast's tail against the reeds which
awakened Tarzan. Jungle folk do not awaken slowly--instantly, full
consciousness and full command of their every faculty returns to
them from the depth of profound slumber.

Even as Tarzan opened his eyes he was upon his feet, his spear
grasped firmly in his hand and ready for attack. Again was he
Tarzan of the Apes, sentient, vigilant, ready.