Otto Loewi

Otto Loewi (June 3, 1873 - December 25, 1961) was a German doctor. He won the 1936 Nobel Prize in Physiology or Medicine, along with Henry Hallett Dale, for their discoveries about chemical transmission of nerve impulses 
In his most famous experiment, Loewi took fluid from a frog heart with a slowed beat and applied it to another. That slowed the second heart. This showed that synaptic signalling used chemical messengers.
It is now known that there are two different kinds of nerve synapses. One kind releases chemicals, and is a neurotransmitter synapse. The other is an electrical synapse which transmits voltage charges over gap junctions between nerve cells.