Exclude every trace of these organisms, and no change occurs.
In other words, are these organisms not spontaneously generated?
All organisms, then, are closely adapted to their surroundings.
A species of Acarus is recorded as infesting a store of powdered strychnine and feeding on that drug, so poisonous to larger organisms. Reference to literature (40).
Differences connected with the mode of supply of nutritive material do exist, but they are mainly correlated with the structure of the organisms, which makes the method of absorption different.