Scientists in the United States have studied the causes of animal hibernation by injecting blood from hibernating ground squirrels into the leg veins of two ground squirrels that had already left hibernation and placing them in a 7  degree cold room  For several days, the two ground squirrels, out of hibernation, went back into hibernation  In June of the same year, blood was taken from the two animals and injected into the leg veins of three active ground squirrels  Although it was summer, the three active ground squirrels went into hibernation again  In July of the same year, five active leg veins were injected from the three animals
When they took blood from hibernating marmots and injected it into active leg veins of ground squirrels, the ground squirrels went into hibernation
The blood of marmots and ground squirrels does not cause rejection.