The law of three stages is an idea developed by Auguste Comte in his work The Course in Positive Philosophy. It states that society as a whole, and each particular science, develops through three mentally conceived stages: (1) the theological stage, (2) the metaphysical stage, and (3) the positive stage.
Electron microscope‘s differ from light microscope’s in that they produce an image of specimen by using a beam of electrons rather than a beam of light. Electrons have such a shorter wavelength than visible light, and this allows electron microscope to produce higher resolution images than standard light microscope‘s
The first living things on Earth, single-celled micro-organisms<span> or microbes lacking a cell nucleus or cell membrane known as prokaryotes, seem to have </span>first<span> appeared on </span>Earth<span> almost four billion years ago, just a few hundred million years after the formation of the </span>Earth<span> itself.</span>
