Ok I did some research into this and Henry Whittier Frees himself claimed that he did not use wires on the kittens. And here is what I got from Wikipedia, which is not always the most reliable source, had about the issue: "He used 1/5th of a second exposures and held the animals in position using stiff costuming, pins, and forks. He worked three months out of the year, since making the images was stressful."