Biogenesis

Biogenesis is any process by which lifeforms produce other lifeforms. For example, a spider lays eggs that become other spiders. Spontaneous generation is a different matter, the ancient Greeks believed that living things could spontaneously come into being from nonliving matter, and that the goddess Gaia could make life arise spontaneously from stones – a process known as Generatio spontanea (which obviously translates to spontaneous generation). Aristotle disagreed, but he still believed that creatures could arise from dissimilar organisms or from soil, and as from the 17th century lots of observations and arguments were placed and many different scientists but out their own experiments.

One of those scientists was Lazzaro Spallanzani. He 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. Critics of Spallazani's work argued his experiments destroyed the "life force" that was required for spontaneous generation to occur. His work paved the way for later research by Louis Pasteur, who defeated the theory of spontaneous generation. He also 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. Spallanzani showed that some animals, especially newts, can regenerate some parts of their body if injured or surgically removed.
Spallanzani is also famous for extensive experiments on the navigation in complete darkness by bats, where he concluded that bats use sound and their ears for navigation in total darkness (see animal echolocation). He was the pioneer of the original study of echolocation, though his study was limited to what he could observe. Later scientists moved onto studies of the sensory mechanisms and processing of this information.

Theordore Schwann seeing