CONFLICT OVER SPONTANEOUS GENERATION (Spontaneous Generation, Francesco Redi, John Needham, Lazaro Spallanzani and Louis Pasteur's Swan Neck Flask Experiment)

 SPONTANEOUS GENERATION

·       “Living organisms can arise from non-living things” is referred as Spontaneous generation (or) Abiogenesis.

·       For example,

ü  Mice from Grains

ü  Beetles from Dust

ü  Worms and Frogs from Mud

ü  Maggots from Rotting meat. 

·        Aristotle (384 – 322 BC) (Greek Philosopher) (Father of Biology) proposed Spontaneous Generation Theory at 350 BC.

·       The microbiology starts when the disprove of Spontaneous Generation theory.

FRANCESCO REDI (1626 – 1697)

·       Francesco Redi (Father of Parasitology) proposed “Theory of Biogenesis” – Life comes from Life in 1665.

·     Francesco Redi was the first who disproved the “Theory of Spontaneous Generation” by showing that if raw meat was protected from flies, the formation of maggots was prevented.

·       He demonstrated that flies did not arise spontaneously from rotting meat by simple experiment. He disproved the Spontaneous generation theory by the below given experiment.

Jar – 1 (Uncovered)

·       Jar Left open.

·       Maggots developed.

·       Flies were observed laying eggs on the meat in the open jar.

Jar – 2 (Covered with Gauze)

·       Jar covered with Gauze.

·       Maggots appeared on the gauze.

·       Flies were observed laying eggs on the meat in the gauze.

Jar – 3 (Tightly sealed)

·       Jar tightly sealed.

·       No maggots observed.

JOHN NEEDHAM (1713 – 1781)

·       In 1745, John Needham (English Biologist and Roman Catholic Priest) boiled the Broth, which contained both plant and animal matter.

·       John Needham believed this brief period of boiling would kill any microorganisms living in the Broth. After the 3 days period, the Broth was cloudy and Needham used a microscope to observe microbes present in the mixture.

·    Needham concluded that “Life Force” (the force that gives strength) present in all Inorganic molecules and tiny organisms had spontaneously generated from the non-living matter of the Broth.

      A                                      B                                        C

A - Boiled conical flask rich in nutrients (Beef broth); B – Conical flask in opened condition and C – Microbial growth was observed in liquid broth.

LAZARO SPALLANZANI (1729 – 1799)

·       In 1769, an Italian Catholic Priest Lazaro Spallanzani challenged the work of John Needham.

·       In his experiment, he boiled the sealed conical flask which contains liquid rich in nutrients (Beef broth) and kept the conical flask in sealed condition. After few days, he does not observe any microbial growth in the liquid broth. From his experiment, he concluded that the microorganisms will not arise spontaneously and arise due to the microorganisms present in air.

A                                         B                                          C

A – Boiled and sealed conical flask rich in nutrients (Broth); B – Conical flask in sealed condition and C – No microbial growth was observed in liquid broth.

LOUIS PASTEUR (1822 – 1895)

·       Louis Pasteur was the “Father of Modern Microbiology”.

·       Louis Pasteur is a Chemistry Professor from France who disproved the Spontaneous Generation Theory completely by his “Swan Neck Flask Experiment”. 

(i)    Broth solutions rich in nutrients were placed in Swan neck flasks and sterilized by boiling. After boiling, the liquid was allowed to cool.

(ii)  After cooling, the liquid was left was several months.

(iii)Dust and microorganisms settle in bend of the flask neck and the liquid present in the Swan neck flask remains sterile.

(iv) Flask was tilted and allowed the liquid to come into contact with deposit in neck.

(v)   Finally, liquid turns cloudy due to microbial growth.

Finally, Spontaneous Generation Theory was disproved by Louis Pasteur.