<P> In the years following Louis Pasteur's experiment in 1862, the term "spontaneous generation" fell into increasing disfavor . Experimentalists used a variety of terms for the study of the origin of life from non-living materials . Heterogenesis was applied to once - living materials such as boiled broths, and Henry Charlton Bastian proposed the term archebiosis for life originating from inorganic materials . The two were lumped together as "spontaneous generation", but disliking the term as sounding too random, Bastian proposed biogenesis . In an 1870 address titled, "Spontaneous Generation", Thomas Henry Huxley defined biogenesis as life originating from other life and coined the negative of the term, abiogenesis, which was the term that became dominant . </P> <P> As part of his overall attempt to give natural explanations of things that had previously been ascribed to the agency of the gods, Anaximander believed that everything arose out of the elemental nature of the universe, which he called the "apeiron" or "unbounded". According to Hippolytus of Rome in the third century CE, Anaximander claimed that living creatures were first formed in the "wet" when acted on by the Sun, and that they were different then than they are now . For example, he claimed humans, in a different form, must have earlier been born mature like other animals, or they would not have survived . Anaximander also claimed that spontaneous generation continued to this day, with aquatic forms being produced directly from lifeless matter . </P> <P> Anaximenes, a pupil of Anaximander, thought that air was the element that imparted life, motion and thought, and speculated that there was a primordial terrestrial slime, a mixture of earth and water, which when combined with the sun's heat formed plants, animals and human beings directly . </P> <P> Xenophanes traced the origin of man back to the transitional period between the fluid stage of the earth and the formation of land . He too held to a spontaneous generation of fully formed plants and animals under the influence of the sun . </P>

Which of the following scientists first challenged spontaneous generation