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.
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.
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.
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.
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.
Pasteur that the occurrence of abiogenesis in the microscopic world was disproved as much as its occurrence in the macroscopic world.
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.
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.
So far the theory of abiogenesis may be taken as disproved.