That they are thus ancillary as well as coexistent today leads us to confront for them a community of origin in the past; and further study confirms the inference. Both paleontology and entomology, or the science of the aged and the science of the young, prove such ancestry to be a fact. By going back from the present into the past, or, what amounts to substantially the same thing, by descending in the scale of life to the lowest known forms of organism, we find proof of concomitance, cogent because congenital. At the time when inorganic chemical compounds first passed by evolution into organic ones, the change was of so general a character that even such tardy representatives of it as survive today tax erudition to tell to which of the two great kingdoms they belong, the vegetal or the animal. Simplest and most primitive of known organisms are the chromacea, unnucleated single cells as Haeckel has shown, and next to them in order come many of the bacteria, also of simple unnucleated plasm. So little do the majority of the bacteria differ morphologically from the chromacea, that on the score of structure the two are not to be catalogued apart. Both are as elemental as anything well can be, which only their diet serves to divide. Each is an organism without organs, thus belying the dictionary definition of both animals and plants. Etymologically they are not organic yet manifestly are alive, and only in their action are unlike. The chromacea are plasm-forming beings, and therefore they are plants; the bacteria are plasm-eating beings, and so are animals. Even this distinction is not always preserved. As Haeckel tells us: “the nitro-bacteria which dwell in the earth having the vegetal property of converting ammonia by oxidation into nitrous acid and this into nitric acid, using as their source of carbon the carbonic acid gas of the atmosphere. They feed, like the chromacea, on simple inorganic compounds.” Here, then, we have, close to the threshold of organic life, unorganized organisms, roughly speaking coeval and differing in a sense but little, either of them, from inorganic crystals; and yet the one is an animal, the other a plant. Progenitors of the two great divisions of life, they were themselves concomitantly evolved, either side by side or as offshoots both of a common stock. Now, if the ancestors of the two great organic kingdoms were thus simultaneously produced here, we are warranted in believing that they would similarly be produced elsewhere, given conditions suitably alike. In consequence, if we detect the presence of the one, we already have an argument for inferring the other. Not to complete our syllogism would be to flaunt a lack of logic in nature’s face.