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.
Answer:
conditioned stimulus
Explanation:
Conditioned stimulus -
It refers to as the neutral stimulus , which triggers or initiates the conditioned response , is referred to as the conditioned stimulus .
Ivan Pavlov was the very first one to give meaning to the term conditioned stimulus , by experimenting on the dogs .
Hence , from the given scenario of the question ,
The correct answer is conditioned stimulus .
Adaptation? Their size plays a role in this, and size is sometimes an adaptation.
Respiratory system and Circulatory system :P