Answer:
Robert Chambers, in the once famous Vestiges of Creation, interested and shocked his contemporaries by his denial of the fixity of species and his insistence on creation by progressive evolution, but had no better theory of the cause of variation than to suppose that organisms - "from the simplest and oldest to the highest and most recent" were possessed of "an inherent impulse, imparted by the Almighty both to advance them from the several grades and modify their structure as circumstances