What is "spontaneous generation"

Generation \Gen`er*a"tion\, n. [OE. generacioun, F. g['e]n['e]ration, fr.L. generatio.]

1. The act of generating or begetting; procreation, as of animals.

2. Origination by some process, mathematical, chemical, or vital; production; formation; as, the generation of sounds, of gases, of curves, etc.

3. That which is generated or brought forth; progeny; offspiring.

4. A single step or stage in the succession of natural descent; a rank or remove in genealogy. Hence: The body of those who are of the same genealogical rank or remove from an ancestor; the mass of beings living at one period; also, the average lifetime of man, or the ordinary period of time at which one rank follows another, or father is succeeded by child, usually assumed to be one third of a century; an age.

   This is the book of the generations of Adam.
   --Gen. v. 1.

   Ye shall remain there [in Babylon] many years, and for a long season, namely, seven generations.
   --Baruch vi. 3.

   All generations and ages of the Christian church.
   --Hooker.

5. Race; kind; family; breed; stock.

   Thy mother's of my generation; what's she, if I be a dog?
   --Shak.

6. (Geom.) The formation or production of any geometrical magnitude, as a line, a surface, a solid, by the motion, in accordance with a mathematical law, of a point or a magnitude; as, the generation of a line or curve by the motion of a point, of a surface by a line, a sphere by a semicircle, etc.

7. (Biol.) The aggregate of the functions and phenomene which attend reproduction.

   Note: There are four modes of generation in the animal kingdom: scissiparity or by fissiparous generation, gemmiparity or by budding, germiparity or by germs, and oviparity or by ova.

   Alternate generation (Biol.), alternation of sexual with asexual generation, in which the products of one process differ from those of the other, -- a form of reproduction common both to animal and vegetable organisms. In the simplest form, the organism arising from sexual generation produces offspiring unlike itself, agamogenetically. These, however, in time acquire reproductive organs, and from their impregnated germs the original parent form is reproduced. In more complicated cases, the first series of organisms produced agamogenetically may give rise to others by a like process, and these in turn to still other generations. Ultimately, however, a generation is formed which develops sexual organs, and the original form is reproduced.

   Spontaneous generation (Biol.), the fancied production of living organisms without previously existing parents from inorganic matter, or from decomposing organic matter, a notion which at one time had many supporters; abiogenesis.

Spontaneous \Spon*ta"ne*ous\ (sp[o^]n*t[=a]"n[-e]*[u^]s), a. [L. spontaneus, fr. sponte of free will, voluntarily.]

1. Proceeding from natural feeling, temperament, or disposition, or from a native internal proneness, readiness, or tendency, without constraint; as, a spontaneous gift or proposition.

2. Proceeding from, or acting by, internal impulse, energy, or natural law, without external force; as, spontaneous motion; spontaneous growth.

3. Produced without being planted, or without human labor; as, a spontaneous growth of wood.

   Spontaneous combustion, combustion produced in a substance by the evolution of heat through the chemical action of its own elements; as, the spontaneous combustion of waste matter saturated with oil.

   Spontaneous generation. (Biol.) See under Generation.

   Syn: Voluntary; uncompelled; willing.

   Usage: Spontaneous, Voluntary. What is voluntary is the result of a volition, or act of choice; it therefore implies some degree of consideration, and may be the result of mere reason without excited feeling. What is spontaneous springs wholly from feeling, or a sudden impulse which admits of no reflection; as, a spontaneous burst of applause. Hence, the term is also applied to things inanimate when they are produced without the determinate purpose or care of man. ``Abstinence which is but voluntary fasting, and . . . exercise which is but voluntary labor.''
   --J. Seed.

   Spontaneous joys, where nature has its play, The soul adopts, and owns their firstborn away.
   --Goldsmith. [1913 Webster] -- Spon*ta"ne*ous*ly, adv. -- Spon*ta"ne*ous*ness, n.

n. (context biology English) the fancied production of living organisms without previously existing parents from inorganic matter, or from decomposing organic matter, a notion which at one time had many supporters; abiogenesis; anomalous generation

n. a hypothetical organic phenomenon by which living organisms are created from nonliving matter [syn: abiogenesis, autogenesis, autogeny]

Spontaneous generation or anomalous generation is an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. Typically, the idea was that certain forms such as fleas could arise from inanimate matter such as dust, or that maggots could arise from dead flesh. A variant idea was that of equivocal generation, in which species such as tapeworms arose from unrelated living organisms, now understood to be their hosts. Doctrines supporting such processes of generation held that these processes are commonplace and regular. Such ideas are in contradiction to that of univocal generation: effectively exclusive reproduction from genetically related parent(s), generally of the same species.

The doctrine of spontaneous generation was coherently synthesized by Aristotle, who compiled and expanded the work of prior natural philosophers and the various ancient explanations of the appearance of organisms; it held sway for two millennia. Today it is generally accepted to have been decisively dispelled during the 19th century by the experiments of Louis Pasteur. He expanded upon the investigations of predecessors (such as Francesco Redi who, in the 17th century, had performed experiments based on the same principles). However, some experimental difficulties were still there and objections from persons holding the traditional views persisted. Many of these residual objections were dealt with by the work of John Tyndall, succeeding the work of Pasteur.

Pasteur's experiment is generally known to have refuted the theory of spontaneous generation in 1859. Disproof of the traditional ideas of spontaneous generation is no longer controversial among professional biologists. By the middle of the 19th century, the theory of biogenesis had accumulated so much evidential support, due to the work of Louis Pasteur and others, that the alternative theory of spontaneous generation had been effectively disproven. John Desmond Bernal suggests that earlier theories such as spontaneous generation were based upon an explanation that life was continuously created as a result of chance events.