Complex sentence: He then found that the effect of removing the brain could be reversed in a transplant experiment that showed that "loose-brain" transplants into the abdomen of a receiving moth showed eclosion rhythms with the phase of the donor moth.
Split into simpler sentences: He then found that this effect could be reversed through "loose-brain" transplants into the abdomen of a receiving moth. This resulted in eclosion rhythms with the phase of the donor moth.