The scientist who explained the thigmonastic movement in Mimosa pudica was Sir Jagadish Chandra Bose, an Indian physicist, biologist, and botanist. Bose conducted a series of experiments in the late 19th and early 20th centuries to study the thigmonastic movement in plants, particularly in Mimosa pudica. He used his invention, the crescograph, to measure plant growth and response to stimuli. He concluded that this response was due to the transmission of an electrical impulse from the point of touch, which triggered the plant's movement. 

Bose's work on plant physiology and thigmonastic movements was groundbreaking and helped pave the way for further research in the field.