The Experiment part 4

Using her legs to pull, the limb pushed deeper, expanding her walls in all directions.
She could feel her organs giving way to fit the limb inside her.
The thrusting increased in intensity as the beast got more excited, almost the whole shaft was inside of her now.
The sack hit her stomach as he rammed in to her.
Once more the beast started ejaculating inside of her, filling her with it's seed.
The hot seed was flowing, making puddles on the floor and running down her thighs and legs, but she could barely feel it as all her senses was directed at the giant limb thrusting furiously in and out of her.
Suddenly the beast paused, pushing intensely as hard as he could to stay inside of her while at the same time pulling her legs towards him.
The recruit almost fainted from the pain when the big load of seed entered her all at once.
She was already so full she could feel it splashing out of her in warm jets of seed.
The beast pulled out of her once more, taking buckets of seed with him.
Once more she felt the relief of having survived, she tried to get up but felt back down on her arms as her muscles failed her.
She looked back between her legs and saw, to her great horror, how the beasts limb was stiffening again.
Her legs where pulled back, her body moving back towards the oncoming intruder.
This time she did not feel it move up against her now trembling opening, but rather against her other hole.
At first the idea did not hit her, but when she felt the tip of the huge limb pushing against her ring, lubing it with the seed, she could feel the fear rushing through her.
She tried to resist with the strength she had left but it was useless, the head was pressing against her and even if she tried to stop it her ring was widening.
As the beast pulled harder the head was now halfway in and seed was starting to make it's way into her.
As the ring was made more and more wet the head pushed deeper and with a sudden jerk the head entered her fully.
She let out a scream of pain as the limb started ramming in and out of her, getting deeper and deeper for each thrust.
It was not long before the shaft was fully submerged inside her.
The sack slapped her opening brutally as the shaft rammed inside of her with incredible force, going from fully inside of her to almost entirely outside, then back in again.