Emma can't help herself. Both she and Mary were notorious for having a reckless streak in college. She takes two of the vials out of the centrifuge and matches them back to their corresponding original, labeled vials.
"Hmm, 'Male' vial, that might be interesting." she said. Emma had always had a problem understanding the opposite sex, having just broken up with her latest boyfriend. As a scientist, she wondered exactly how much of a difference the hormones actually made. But that didn't seem like enough, Emma still felt something more was needed. She carefully noted the selection of vials and makes a decision on 'Lion.' Emma takes the 'lion' vial and measures out half of the vial's liquid into a sterile graduated cylinder. "No need to go all the way to animal," she thought, remembering how well the anthro form looked on Mary. Emma then takes the 'male' vial and empties the vial into the graduated cylinder, and pours the liquid into a beaker to stir it.
Emma gets a pen and pad of paper ready as well as turning on a tape recorder. At first she wishes she had a video camera, but then is thankful she doesn't because she realizes she will have to strip naked or have her clothing torn apart. Luckily, Emma has placed a cot in her lab for she often works late into the night and doesn't have the energy to go to her bedroom. She sits on the cot, now completely stripped, takes a breath, and drinks the liquid in the beaker. She places the beaker on the floor and giggles nervously as she thinks about what she has just done.
A warm sensation spreads across Emma's body as she notes her breasts beginning to recede and her muscle mass starting to increase. She feels a tickle on her face and feels the beginnings of facial hair. She watches intently as her clean shaven legs start to grow what appear to be tawny colored hairs. "Intriguing," she says, leisurely taking notes, "but I thought it would go faster than this." Suddenly, Emma feels a sort of tightness in her crotch that she has trouble describing. She reclines a little and watches in amazement as her vagina begins to seal itself shut from the bottom-up. Not only that, the area is also starting to bulge outward. Her breasts are now totally receded, and she is still growing in size. Another indescribable feeling erupts in her feet, and Emma is able to divert her attention from her crotch to observe her feet elongating as well as growing larger.
Emma has completely stopped taking notes on her notepad as the changes now race across her body. Her long hair is now draping her growing shoulders and is actually starting to integrate with them. Her growing beard is also starting to mingle with the fur sprouting on her now masculine chest. Emma's vagina finishes its transition into an animalistic sheath complete with an impressively sized scrotum. She reluctantly touches the furry sac, confirming her gender change, and feels a faint stirring of her new internal organs. Now a new sensation presents itself at the base of 'his' spine which promptly makes him roll over onto his stomach. Deepening moans escape Emma's lips as he feels a very accelerated cellular process develop a flexible, new appendage.
During the construction of the tail, Emma's legs have now completely metamorphosed from plantigrade to digitigrade form. His feet have supple pads on the bottom, and his toe nails have re-shaped and recessed into the flesh of his toes to become retractable claws. The same is now occurring to his hands as the flesh on the palms thickens into pads. Emma can slightly feel the retractable claws sliding in and out of his fingertips as he clenches his fists at the overwhelming sensation of the elongating tail. Emma also feels a faint tickling as his ears reposition and re-shape themselves through his thick mane of hair on his head. Emma's body has now almost completely gained a full coating of tawny colored lion fur.
Emma can hear the deep masculine tone of his voice as he lies on the cot breathing heavily as the tail reaches its final length and starts twitching, giving Emma new and strange feelings. Emma wonders if it is over, but is quickly answered by a numbness in his face. It is as if all of the muscles in his head have gone slack. Emma pushes himself up with his muscular arms, and looks cross-eyedly as his facial bones expand to form the powerful muzzle and jaws of a lion. Although his tongue is limp, Emma can faintly feel his teeth becoming the teeth of a carnivore. He finally feels the muscles in his face tighten back up, now modified for his new skull.
Emma, still panting from the transformation, sits up on the cot trying to be aware of his new tail. He shakily gets to his feet, needing a moment to determine his new center of gravity. Looking up and down his new body, Emma sees that his mane covers his shoulders and a length of shaggy hair from his mane actually runs all the way down his chest and belly to his crotch which also has a covering of shaggy fur. He has well-defined muscles all over his body, and he wastes no time in flexing and stretching some of them.
"Very fascinating." Emma says in a deep masculine voice. He takes in a deep wiff of his strong male lion scent. "Now to do some tests."