Paul look back and sees a lump growing in the back of his pants. It gets longer and he feels the pressure, then the spasms at it starts slithering around inside his clothes. He takes off his pants to see what's happened, and he is shocked by the sight of a long, bony protrusion from his spine. It's a 7-inch, hairless tail: his human skin stretched taught over surprising new vertebrae. It's swishing around wildly in every direction. He reaches around trying to grab it with his right hand. When he finally gets a grip, the feeling of skin on skin--from both hand and tail--confirm the reality of what has just happened.
The skinny appendage sqiurms around on its own for a bit, seemingly trying to get free, then comes to a rest in Paul's intrigued grasp. He bends it around with his hand--up, down, left, right--as though he were bending a rope, except he can *feel* every motion through his growing spine.
The change is far from over. His tail has been extending even while he's been playing with it. Using both hands to hold it, he starts to feel (and see) dark hairs starting to grow from his skin. They grow in fastest at the tip, creating a substantial tassel already. Paul brushes his left hand against the tassel. It feels stiffer and coarser than his natural hair. He plucks one of the hairs as a test: ouch!
Finally Paul releases his new tail and lets it hang down limply between his legs, swaying slightly. It's no longer spasming uncontrollably, and Paul realises he's gained some coordination in his new appendage. He exercises his new muscles, and his tail flips upward and slaps against his back! A smaller effort just causes the tail to swing back and forth. Looking down at it again, Paul sees that it hangs almost to the ground, and the skin has grown coarser and the fur denser. His tail is surprisingly thick but very ropey, almost like those of the cattle on his aunt's farm.
That's it! Paul knew his tail looked familiar. "I've got a bull's tail!" he realises. "Could this be real?" But he knows it's real, his senses have told him so. He's felt what the cattle felt when they swatted flies off their backs. He's even held it in his still-human hands!
"What else is going to change?" Paul thinks as he snorts suddenly. He reaches up and, feeling his face, discovers that his nostrils have opened broader. He's still taking in the new scents, when...