So far the theory of abiogenesis may be taken as disproved.
Pasteur that the occurrence of abiogenesis in the microscopic world was disproved as much as its occurrence in the macroscopic world.
van Leeuwenhoek discovered bacteria, and it was soon found that however carefully organic matter might be protected by screens, or by being placed in stoppered receptacles, putrefaction set in, and was invariably accompanied by the appearance of myriads of bacteria and other low organisms. As knowledge of microscopic forms of life increased, so the apparent possibilities of abiogenesis increased, and it became a tempting hypothesis that whilst the higher forms of life arose only by generation from their kind, there was a perpetual abiogenetic fount by which the first steps in the evolution of living organisms continued to arise, under suitable conditions, from inorganic matter.
Parker (Elementary Biology) cites a passage from Alexander Ross, who, commenting on Sir Thomas Browne's doubt as to "whether mice may be bred by putrefaction," gives a clear statement of the common opinion on abiogenesis held until about two centuries ago.
The first step in the scientific refutation of the theory of abiogenesis was taken by the Italian Redi, who, in 1668, proved that no maggots were "bred" in meat on which flies were prevented by wire screens from laying their eggs.
Huxley, who took a large share in the process of refuting contemporary abiogenesis, have stated their belief in a primordial archebiosis.
Under the heading of Abiogenesis is discussed the series of steps by which the modern acceptance of biogenesis and rejection of abiogenesis has been brought about.
From the 17th century onwards it was gradually shown that, at least in the case of all the higher and readily visible organisms, abiogenesis did not occur, but that omne vivum e vivo, every living thing came from a pre-existing living thing.
The refutation of abiogenesis has no further bearing on this possibility than to make it probable that if protoplasm ultimately be formed in the laboratory, it will be by a series of stages, the earlier steps being the formation of some substance, or substances, now unknown, which are not protoplasm.
Such intermediate stages may have existed in the past, and the modern refutation of abiogenesis has no application to the possibility of these having been formed from inorganic matter at some past time.
None of the people who did crucial experiments on spontaneous generation disproved abiogenesis.
Aristotle explicitly taught abiogenesis, and laid it down as an observed fact that some animals spring from putrid matter, that plant lice arise from the dew which falls on plants, that fleas are developed from putrid matter, and so forth.
ABIOGENESIS, in biology, the term, equivalent to the older terms "spontaneous generation," Generatio aequivoca, Generatio primaria, and of more recent terms such as archegenesis and archebiosis, for the theory according to which fully formed living organisms sometimes arise from not-living matter.
It must be noted, however, that this disproof relates only to known existing organisms. All these are composed of a definite substance, known as protoplasm, and the modern refutation of abiogenesis applies only to the organic forms in which protoplasm now exists.
The nature of sterilization, and the difficulties in securing it, as well as the extreme delicacy of the manipulations necessary, made it possible for a very long time to be doubtful as to the application of the phrase omne vivum e vivo to the microscopic world, and there still remain a few belated supporters of abiogenesis.
It is plain that we cannot discuss adequately the origin of life or the possibility of the artificial construction of living matter (see Abiogenesis and Biogenesis) until the chemistry of protoplasm and specially of proteid is more advanced.
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