And then he was a cat,

The possessing of another species came as quite the shock, the odd focus and lack of colors,the intruding scents and the mind of the beast itself struggling for control of the body Jacob had rudely and suddenly occupied.

Seething and reeling the poor creature threw itself from the windowsill it had been happily occupying before the intrusion, Jacob managed a scream which came out of the cat as a strained meow-ling sound before it landed harmlessly on its feet upright.
In that recovery the last of the cats will was dominated by his own, he was now in full control.
If the professor was correct once Jacob departed his new host the cat would hardly recall this invasion at all, at least this had been the case with all the human subjects, it wasn’t like they could question the cat after the fact.

Looking about himself Jacob spotted some curious children nearby watching his cat probably since it had fallen, he quickly retreated away from them strangely embarrassed and into the unknown….