Spontaneous Generation Vs Biogenesis

The wonderful discovery of microbes both generated and spurred enough interest not only in the
fundamental origin of ‘living things’ but also augmented argument and speculation alike.
Based upon the various experimental evidences the following observations were duly made by
scientists as enumerated below :
John Needham (1713-1781) : Precisely in the year 1749, while experimenting with raw meat
being exposed to hot ashes, he observed meticulously the appearance of organisms that were not present
at the initial stages; and, therefore, inferred that the bacteria virtually originated from the raw meat itself.
Lazaro Spallanzani (1729-1799) : actually boiled ‘beef broth’ for a duration of 60 minutes,
and subsequently sealed the flasks tightly. After usual incubation for a certain length of time, practically
no microbes appeared. However, Needham never got convinced with Spallanzani’s findings, and
vehemently insisted that ‘air’ happened to be an essential component to the process of spontaneous
generation of the microbes, and that it had been adequately excluded from the flasks by sealing them
precisely by the later.
Franz Schulze (1815-1873) and Theodor Schwann (1810–1882) : these two scientists independently
fully endorsed and justified the earlier findings of Spallanzani by allowing air to pass through
strong acid solutions into the boiled infusions, and by passing air into the flasks via red-hot tubes
respectively (Fig. 1.A). In neither instance did microorganisms appear.

H. Schröder and T. von Dusch (~ 1850) : carried out a more logical and convincing experimental
design by passing air via cotton fibers so as to prevent the bacterial growth ; and thus, it ultimately
initiated and gave rise to a basic technique of ‘plugging’ bacterial culture tubes with ‘cotton plugs’
(stoppers), which technique being used still as to date (Fig. : 1.B).
Felix Archimede Pouchet (1800–1872) : revived once again the concept and ideology of spontaneous
generation via a published comprehensive and extensive research article thereby proving its
occurrence. Pasteur (1822–1895) carried out a number of experiments that virtually helped in concluding
the on-going argument once for all time. Pasteur designed a flask having a long and narrow gooseneck
outlet (Fig. : 1.C). Thus, the nutrient broths were duly heated in the above specially–designed flask,
whereby the air — untreated and unfiltered — may pass in or out but the germs settled in the ‘very
gooseneck’ ; and, therefore, practically no microbes ultimately appeared in the nutrient broth (solution).
John Tyndall (1820-1893) : conducted finally various well planned experiments in a specifically
designed box (Fig. : 1.D) to establish and prove the fact that ‘dust’ actually contained and carried
the ‘microbes’ (i.e., germs). He subsequently demonstrated beyond any reasonable doubt that in a
particular situation whereby absolutely no dust was present, the sterile nutrient broth could remain
free of any sort of microbial growth for an indefinite length of time.