THEORY OF BIOGENESIS -

• This theory explains that the existing living organisms originated from pre-existing living beings not from non living entities.
• This concept of origin of life was supported by various evolutionists on the basis of their experiments.
• All such evolutionists have rejected the concept of autogenesis or abiogenesis.
• F. Redi (1626-98) conducted an experiment in which he cooked some meat so that no organisms were left alive and placed them in three jars; one jar left uncovered, one jar was covered with muslin cloth and the third jar covered with parchment paper.
• After a week, he observed that maggots appeared only in that jar which was uncovered not in those jars that were covered by either muslin cloth or parchment paper.
• He concluded that flies arise from the eggs laid down by parent flies in the uncovered jar. On the basis of this experiment Redi had discarded the concept of spontaneous generation.

• Lazzaro Spallanzani (1729-99) prepared a nutritive broth of vegetables and flesh and placed it in flasks and sealed the necks of the flasks just to check the entry of air. He boiled the broth for four hours and left these flasks as such for many days.
• He observed that no living organisms appeared in broth of flasks and hence he concluded that microorganisms are formed not spontaneously, but from those already present in the air.
• Louis Pasteur (1822-95) refused the concept of spontaneous generation on the basis of an experiment.
• He has taken a mixture of sugar and yeast syrup and put this mixture into S-shaped flask.
• The contents of the flask were boiled till steam passed out the tube and then they were cooled.
• Pasteur did not found any change in the content of the flaks after a considerable longer period of time and no growth of organisms was observed.
• He concluded his experiment with an inference that when the air entered the flask, all air-born particles got stuck at the bend of the tube and only the pure air reached the syrup that remained sterile.
• He broke the neck of the flask.
• This made a direct contact of syrup with the air and a thick growth of microorganisms appeared in the flask.
• By this experiment and result, Pasteur conclusively disproved the idea of spontaneous generation.