Lazzaro Spallanzani (1729-1799) was an Italian Catholic priest, biologist and physiologist who made important contributions to the experimental study of bodily functions, animal reproduction, and essentially discovered echolocation. His research of biogenesis paved the way for the investigations of Louis Pasteur. Spallanzani researched the theory about the spontaneous generation of cellular life in 1768. His experiment suggested that microbes move through the air and that they could be killed through boiling. He discovered and described animal (mammal) reproduction, showing that it requires both semen and an ovum. He was the first to perform in vitro fertilization, with frogs, and an artificial insemination, using a dog. He was the pioneer of the original study of echolocation. In 1780 he published, Dissertationi di fisica animale e vegetale, wherein he first interpreted the process of digestion. He proved it was not just a mechanical process of trituration (grinding up the food), but one of actual chemical solution, taking place primarily in the stomach, by the action of the gastric juice. He died from bladder cancer in 1799. After his death, his bladder was removed for study by his colleagues, after which it was placed on public display in a museum in Pavia, where it remains to this day.