It had gripped savagely hold of him and was about to wreak upon him some terrific hurt.

Growth was now routed by fear, and he ki-yi'd like any frightened puppy.
The unknown bore him on he knew not to what frightful hurt, and he yelped and ki-yi'd unceasingly.

This was a different proposition from crouching in frozen fear while the unknown lurked just alongside.

Now the unknown had caught tight hold of him.

Silence would do no good.